For what value of k are the roots of the quadratic
equation kx²+ 4x+ 1=0 equals and reals."

Answers

Answer 1

Answer:

k ≥ 4

Step-by-step explanation:

A Quadratic equation is given to us and we need to find out the value of k for which the equation has real roots. The given equation is ,

[tex]\rm\implies kx^2 +4x +1=0[/tex]

With respect to Standard form of Quadratic equation :-

[tex]\rm\implies ax^+bx+c=0[/tex]

For real roots ,

[tex]\rm\implies Discriminant = b^2-4ac\geq 0[/tex]

Substitute the respective values ,

[tex]\rm\implies b^2-4ac \geq 0\\[/tex]

[tex]\rm\implies 4^2 - 4(k)(1) \geq 0 \\[/tex]

Simplify the LHS ,

[tex]\rm\implies 16 - 4k \geq 0 \\[/tex]

Add 4k both sides ,

[tex]\rm\implies 4k\geq 16 [/tex]

Divide both sides by 4 ,

[tex]\rm\implies \boxed{\blue{\rm k \geq 4}}[/tex]


Related Questions

the ratio of 62 miles to 100 kilometers

Answers

9514 1404 393

Answer:

  0.99779328

Step-by-step explanation:

The exact conversion factor is ...

  1 mi = 1.609344

Then 62 miles is 62×1.609344 km = 99.779328 km.

The ratio of this to 100 km is ...

  99.779328/100 = 0.99779328 . . . . ratio of 62 miles to 100 km

Classify the polynomial 5x3 + 4x - 2 by degree.

Answers

Answer:

3

Step-by-step explanation:

3 would be the degree of the polynomial since it has the highest degree.

Help!!!! Please!! Thanks

Answers

never saw an indian guy asking for help in so simple question

Step-by-step explanation:

ans of 3rd   given statement is true, conclusion, mb=nb

ans of 4th    given statement is true, conclusion alt int angles of paralel lines are equal

AB=BA
∠ABM=∠ABN
MB=NB
△AMB≌△ANB (SAS)

∠CBM=∠ADM
∠BCM=∠DAM
∠BMC=∠DMA
△BCM∽△DAM (AAA)

Hope my answer helped u :)

Express 12 000 iin standard form?​

Answers

Answer:

the answer will be

1.2x10⁴

hope it helps

Answer:

We have been provided the number, 3430000. Therefore, the standard form is, 3430000=3.43×106, here, we have moved 6 places to the left. Hence, the standard form of 3430000 is 3.43×106. Note: It is important to note that the standard form of representing numbers is also called scientific form or standard index form.

please help me with that

Answers

Answer:

[tex]\frac{16}{81}[/tex]

Step-by-step explanation:

[tex](\frac{27}{8} )^{-\frac{4}{3} }[/tex]

[tex]=((\frac{3}{2} )^3)^{-4/3}[/tex]

[tex]=(\frac{3}{2} )^{-4}[/tex]

[tex]=(\frac{2}{3} )^{4}[/tex]

[tex]=\frac{16}{81}[/tex]

Answer:

16/81

Step-by-step explanation:

a negative exponent means 1/...

the number in the numerator means "to the power of".

the number in the denominator means take the root of that power.

so, we have to take the third root of the expression, or this then to the power of 4, and finally build 1/... if the whole result.

and the sequence is not making a difference.

the third root of of 27/8 = 3/2

this to the power of 4 = 81/16

this 1/... = 16/81

sin^6x + cos^6x = 1/4

Answers

Answer:

[tex]\displaystyle x = \frac{\pi}{4} + k\, \pi[/tex] for integer [tex]k[/tex] (including negative numbers.)

Step-by-step explanation:

Pythagorean Identity: [tex]\sin^{2}(x) + \cos^{2}(x) = 1[/tex]. Equivalently, [tex]\cos^{2}(x) = 1 - \sin^{2}(x)[/tex].

Rewrite the original equation and apply this substitution to eliminate [tex]\cos(x)[/tex]:

[tex]\displaystyle \sin^{6}(x) + \cos^{6}(x) = \frac{1}{4}[/tex].

[tex]\displaystyle (\sin^{2}(x))^{3} + (\cos^{2}(x))^{3} = \frac{1}{4}[/tex].

[tex]\displaystyle (\sin^{2}(x))^{3} + (1 - \sin^{2}(x))^{3} = \frac{1}{4}[/tex].

Let [tex]y = \sin(x)[/tex] ([tex]-1 \le y \le 1[/tex].) The original equation is equivalent to the following equation about [tex]y[/tex]:

[tex]\displaystyle y^{6} + (1 - y^{2})^{3} = \frac{1}{4}[/tex].

Expand the cubic binomial in the equation:

[tex]\displaystyle y^{6} + 1 - 3\, y^{2} + 3\, (y^{2})^{2} - (y^{2})^{3} = \frac{1}{4}[/tex].

[tex]\displaystyle y^{6} + 1 - 3\, y^{2} + 3\, y^{4} - y^{6} = \frac{1}{4}[/tex].

Simplify to obtain:

[tex]\displaystyle 1 - 3\, y^{2} + 3\, y^{4} = \frac{1}{4}[/tex].

Rearrange and simplify:

[tex]12\, y^{4} - 12\, y^{2} + 3 = 0[/tex].

[tex]3\, (2\, y^{2} - 1)^{2} = 0[/tex].

[tex]2\, y^{2} - 1 = 0[/tex].

[tex]\displaystyle y^{2} - \frac{1}{2} = 0[/tex].

Solve for [tex]y[/tex]:

Either [tex]\displaystyle y = \frac{1}{\sqrt{2}}[/tex] or [tex]\displaystyle y = -\frac{1}{\sqrt{2}}[/tex].

If [tex]\displaystyle \sin(x) = y = \frac{1}{\sqrt{2}}[/tex], then [tex]\displaystyle x = \frac{\pi}{4} + 2\, k\,\pi[/tex] for all [tex]k\in \mathbb{Z}[/tex].

On the other hand, if [tex]\displaystyle \sin(x) = y = \frac{1}{\sqrt{2}}[/tex], then [tex]\displaystyle x = \frac{3\, \pi}{4} + 2\, k\,\pi = \frac{\pi}{4} + (2\, k + 1) \, \pi[/tex] for all [tex]k\in \mathbb{Z}[/tex].

Combine both situations to obtain:

[tex]\displaystyle x = \frac{\pi}{4} + 2\, k\, \pi[/tex] for all [tex]k \in \mathbb{Z}[/tex].

The equation y=2(x-1)^2-5y=2(x−1)
2
−5y, equals, 2, left parenthesis, x, minus, 1, right parenthesis, squared, minus, 5 is graphed in the xyxyx, y-plane. Which of the following statements about the graph is true?

Answers

Answer:

(b) It is symmetrical about [tex]x = 1[/tex]

Step-by-step explanation:

Given

[tex]y = 2(x - 1)^2 - 5[/tex]

See attachment for options

Required

True statement about the graph

First, we check the line of symmetric

[tex]y = 2(x - 1)^2 - 5[/tex]

Expand

[tex]y = 2(x^2 - 2x + 1) - 5[/tex]

Open bracket

[tex]y = 2x^2 - 4x + 2 - 5[/tex]

[tex]y = 2x^2 - 4x -3[/tex]

A quadratic equation [tex]y = ax^2 + bx + c[/tex] has the following line of symmetry

[tex]x = -\frac{b}{2a}[/tex]

By comparison, the equation becomes:

[tex]x = -\frac{-4}{2*2}[/tex]

[tex]x = \frac{4}{4}[/tex]

[tex]x = 1[/tex]

Hence, the line of symmetry is at: [tex]x = 1[/tex]

(b) is true.

Answer: It is symmetrical about x=1

Step-by-step explanation:

Let be the density function for the shelf life of a brand of banana which lasts up to weeks. Time, , is measured in weeks and . Incorrect answer icon Your answer is incorrect. Find the mean shelf life of a banana using . Round your answer to one decimal place. Mean

Answers

The question is incomplete. The complete question is :

Let [tex]p(t) = -0.0375t^2 + 0.225t[/tex]  be the density function for the shelf life of a brand of banana which lasts up to 4 weeks. Time, t, is measured in weeks and [tex]$0 \leq t \leq 4$[/tex]. Incorrect answer icon Your answer is incorrect. Find the mean shelf life of a banana using . Round your answer to one decimal place.

Answer:

2.4

Step-by-step explanation:

 Given :

[tex]p(t) = -0.0375t^2 + 0.225t[/tex]

Mean :

[tex]$=\int_0^4 tp (t) \ dt$[/tex]

[tex]$=\int_0^4 t (0.0375 t^2 + 0.225t) \ dt$[/tex]

[tex]$=-0.0375 \int_0^4 t^3 \ dt + 0.225 \int_0^4 t^2 \ dt$[/tex]

[tex]$=-0.0375 \left[ \frac{t^4}{4} \right]^4_0 + 0.225 \left[ \frac{t^3}{3} \right]^4_0$[/tex]

[tex]$=-0.0375 (64) + 0.225 \left( \frac{64}{3} \right)$[/tex]

[tex]$=-2.5 + 4.8$[/tex]

= 2.4

Therefore, the mean is 2.4

find H.C.F OF 4x²y and xy²​

Answers

Answer:

xy

Step-by-step explanation:

The HCF is known as the highest common factor. To find the HCF of two values, we have to take the greatest number that fits into all of their factors.

To start, we can list each value's factors.

For 4x²y, this can also be written as 4*x²*y = 4*x*x*y. In multiplication, we can take the factors of each value that is multiplied. Therefore, we can start with the factors of 4 and then go to the factors of x² and so on. Our factor list is thus 1,2,4,x,x²,y

Similarly, for xy² = x*y*y, our factors are x, y, and y²

The common factors for each of these are x and y. Assuming all values are positive and greater than 1, the x*y will be greater than either x or y. Therefore, the highest common factor would be x*y = xy

Given the functions below, find f(x) + g(x)
f(x) = 3x - 1
g(x) = x2 + 4

Answers

Answer:

x^2+3x+3

Step-by-step explanation:

f(x) = 3x - 1

g(x) = x^2 + 4

f(x) + g(x) = 3x-1+ x^2 +4

                 Combine like terms

                   = x^2+3x+3

If ∠AFB and ∠DFE are congruent, what term describes ∠BFE and ∠AFD?

Answers

Answer:

If you add a picture I can help

Step-by-step explanation:

I need to see what the figure looks like

please helpp!!!!!!!!​

Answers

Step-by-step explanation:

the answer is in picture

The option which is not a solution of the equation 2x + 3y = 6 is:
(A) (0, 2)
(B) (1, 1)
(C) (-3, 4)
(D) (3, 0).​

Answers

Answer:

Step-by-step explanation:

B OR TRUE

Look at photo I tested each thing, your answer to this question in option B

What is the result of rounding 8,888,888 to the nearest ten?

Answers

Answer:

8,888,890

Step-by-step explanation:

yup yup

Find the approximate side length of a square game board with an area of 145 in 2 Plz help!

Answers

Answer:

Side length ≈ 12.04

Step-by-step explanation:

145 = x²

144 is the closest  square, with the root 12

The square root of 145 is approximately 12.04

If my answer is incorrect, pls correct me!

If you like my answer and explanation, mark me as brainliest!

-Chetan K

Answer:

The approximate side length is 12.0 in

Step-by-step explanation:

The area of a square is given by

A = s^2  where s is the side length

145 = s^2

Taking the square root of each side

sqrt(145) = sqrt(s^2)

12.04159458 = s

The approximate side length is 12.0 in

Solve the following.
2x^2-7x-4/6x^2+7x+2<0
Can someone explain how to solve this.

Answers

Answer:

Which one have same variable gather or decrease up

Step-by-step explanation:

2x^2-4.6x^2=1.4x^2

-7x+7x=0

1.4x^2+2<0

x<0

i am having troubles solving this 4(x+3)=x+42 can i get some help please.

Answers

Answer:

x=10

Step-by-step explanation:

Step 1: Multiply 4 with X and 3. You'll get 4x+12=x+42

Step 2: Keep the variable on one side and the number on the other side. you would subtract X and subtract 12. You'll get 3x=30

Step 3: Divide by the 3 on both sides and you'll get x=10

Given:

[tex] \\ ⇢ \tt \: 4(x + 3) = x + 42 \\ [/tex]

Solution:

[tex] \\ ⇢ \tt \: 4(x + 3) = x + 42 \\ \\ \\ \tt⇢ 4x + 12 = x + 42 \: \: \\ \\ \\ \tt \: ⇢4x - x = 42 - 12 \: \\ \\ \\ \tt \: ⇢3x = 30 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \\ \tt \: ⇢x = \frac{30}{3} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \\ \tt \: \pink{ \pmb{ \mathfrak{⇢x = 10}}} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \\ [/tex]

Verification:

[tex] \\ ⇢ \tt \: 4(10+ 3) = 10+ 42 \\ \\ \\ \tt⇢ 40 + 12 = 10 + 42 \: \: \\ \\ \\ \tt \: ⇢52 = 52 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \\ \: ⇢ \purple{ \pmb{ \bold{L.H.S = R.H.S}}}\\ \\ \\ [/tex]

Hence Verified!

Simplify: 0.9(2b-1)-0.5b+1

Answers

Answer:

Step-by-step explanation:

0.9*2b = 1.8b

0.9*-1 = -0.9

So far we have 1.8b-0.9. It can't be simplified further.

Then, we add the 2nd part, -0.5b+1.

We have:

1.8b-0.9-0.5b+1. Next we combine like terms.

1.8b-0.5b = 1.3b.

-0.9+1 = 0.1

Then we put it together.

1.3b+0.1 is our answer.

Hope this helped! Have a nice day :D

Hi there!  

»»————- ★ ————-««

I believe your answer is:

1.3b + 0.1

»»————- ★ ————-««  

Here’s why:  

⸻⸻⸻⸻

[tex]\boxed{\text{Simplifying...}}\\\\0.9(2b-1)-0.5b+1\\--------------\\\rightarrow 1.8b - 0.9 - 0.5b + 1\\\\\rightarrow 1.8b - 0.5b - 0.9 + 1\\\\\rightarrow \boxed{1.3b +0.1}[/tex]

⸻⸻⸻⸻

»»————- ★ ————-««  

Hope this helps you. I apologize if it’s incorrect.  

From the table below, determine whether the data shows an exponential function. Explain why or why not. x 3 1 -1 -3 y 1 2 3 4 a. No; the domain values are at regular intervals and the range values have a common sum 1. b. No; the domain values are not at regular intervals. c. Yes; the domain values are at regular intervals and the range values have a common factor 2. d. Yes; the domain values are at regular intervals and the range values have a common sum 1. Please select the best answer from the choices provided A B C D

Answers

A………………………………………………….

Answer:

C

Step-by-step explanation:

you find the variable

what is the solution to the equation below? sqrt x-7 = 5
A. 144
B. 12
C. 2
D. 4

Answers

Answer:

I think the answer is B.12

If this not correct, Sorry.

PT= 3x+4 and TQ=5x-8

Answers

Answer:

So if PT=TQ and TQ=7x-9

PT=5x+3=TQ=7x-9

5x+3=7x-9

minus 5x both sides

3=2x-9

add 9 both sides

12=2x

divide 2

6=x

PT=5x+3

PT=5(6)+3

PT=30+3

PT=33

PT=QT=33

x=6

Hoped I helped you.

Find the surface area of the composite figure

Answers

Answer:

384 cm^2

Step-by-step explanation:

Start with the prism (I multiply by 2 because some of the surfaces are more of):

4×15×2=1206×15×2=1806×4=24

The Triangular Prism (I divide by 2 because it is a triangle shape on the sides):

3×4/2*2=123×6=186×5=30

The Last Step (adding everything):

120+180+24+12+18+30=384

Harold used 6 centimeters of tape to wrap 3 presents. What is the unit rate?

Answers

Answer:

2cm/present is the unit rate

[tex]\huge\text{Hey there!}[/tex]

[tex]\huge\text{Harold used \underline{\underline{6 centimeters of tape}} to wrap}\\\huge\text{\underline{\underline{3 presents}}. \underline{\underline{\underline{What is the unit rate?}}}}[/tex]

[tex]\huge\boxed{\star \ Formula: \mathsf{\dfrac{a}{b}= unit\ rate \ }\star}[/tex]

[tex]\huge\boxed{\mathsf{Equation\boxed{\rightarrow}\ \dfrac{6}{3} = \boxed{unit\ rate}}}[/tex]

[tex]\huge\boxed{\mathsf{\dfrac{6}{3} = \boxed{\bf unit\ rate}}}\\\\\\\huge\boxed{\mathsf{ 6 \ \boxed{\div} \ 3\ \boxed{= } \ \bf\boxed{\bf unit\ rate}}}\\\\\\\\\huge\boxed{\boxed{=} \bf \ 2}[/tex]

[tex]\huge\boxed{\star\ \textsf{Therefore, the UNIT RATE IS: \bf \boxed{\bf 2}}\ \star}[/tex]

[tex]\boxed{\boxed{\huge\text{Answer: the unit rate is \bf \boxed{\underline{\underline{\underline{\underline{\bf 2}}}}}}}}\huge\checkmark\\\\\huge\text{Good luck on your assignment \& enjoy your day!}\\\\\\\\\huge\boxed{\frak{Amphitrite1040:)}}[/tex]

( 2 + 3 ) ^-1 x ( 2 ^-1 + 2^-1 )

Answers

Answer:

Step-by-step explanation:

[tex]\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\la\la\la\la\ddddddddddddddddddddddddddddddddcleverdddddd\ffffffffffffffffffffffffffffffffffffffff\pppppppppppppppppppppppppppppppppppp\ddddddddddddddddddd\displaystyle\ \Large \boxed{ \boxed{\boldsymbol{Rule : a^{-1}=\frac{1}{a} }}} \\\\\\\\ (2+3)^{-1} \times (2^{-1}+2^{-1}) = \\\\1)\ (2+3)^{-1}=5^{-1}=\frac{1}{5} \\\\2)\ 2^{-1}+2^{-1}=\frac{1}{2} +\frac{1}{2} } =1 \\\\3)\ \frac{1}{5} \cdot 1=\boxed{\frac{1}{5} }[/tex]

Please help explanation if possible

Answers

Answer:

17.6

Step-by-step explanation:

Answer:

80 pennies ; 160 nickels

Step-by-step explanation:

Given the 2 equations

0.01p + 0.05n = 8.80 → (1)

n = 2p → (2)

Substitute n = 2p into (1)

0.01p + 0.05(2p) = 8.80

0.01p + 0.1p = 8.80

0.11p = 8.80 ( divide both sides by 0.11 )

p = 80

Substitute p = 80 into (2)

n = 2 × 80 = 160

There are 80 pennies ; 160 nickels


There is a sequence of rigid transformations that takes A to A', B to B', and C to "
same sequence takes D to D'. Draw and label D':

Answers

Answer:

I think it's D

Step-by-step explanation:

Answer:  I think its D

Step-by-step explanation:

Rigid transformation moves a shape without changing the size of the shape.

See attachment for the diagram that shows the position of D'

A(-3,3),b(0,1) and c(-1,-4)

Answers

Step-by-step explanation:

domain (-3,0,-1)

range (3,1,4)

Find the largest integer not greater than the following expression :
[tex]\displaystyle \large \boldsymbol{} \frac{2150}{2005} +\frac{2150}{2006} +\frac{2150}{2007 } + ...+\frac{2150}{2020}[/tex]

Answers

Answer:

17

Step-by-step explanation:

The number of terms:

2020 - 2004 = 16

Each term is greater than 1, so the expression is greater than 16:

2150/2005 = 1 + 145/20052150/2006 = 1 + 144/2006...2150/2020 = 1 + 130/2020

It's easy to note each of the numbers getting smaller like 145/2005 > 144/2006 etc. Taking the smallest fraction.

The sum is:

S > 16 + 16*130/2020 = 16 + 2080/2020 > 16 + 1 = 17

So the largest integer not greater than S is 17.

Can someone help me on this

Answers

Answer:

The choose (C)

F(x)=x/ (x+1)(x-2)

If mAngleVUW = (4x + 6)° and mAngleWUT = (6x – 10)°, what is the measure of AngleWUT?

Answers

Answer:

2 is the answer........

Answer:

the answer is 38 degrees

Step-by-step explanation:

just took test on ed

Other Questions
A man was sitting with his feet up on a desk. He turned his head when Stanley and the guard entered, but otherwise didn't move. Even though he was inside, he wore sunglasses and a cowboy hat. He also held a can of soda, and the sight of it made Stanley even more aware of his own thirst.. . .There must have been a small refrigerator behind his desk, because the man in the cowboy hat produced two more cans of soda. For a second Stanley hoped that one might be for him, but the man gave one to the guard and said the other was for the driver.Holes,Louis SacharWhat do the actions of the man in the cowboy hat show about him?He is considerate of others.He is cold to everyone.He is indifferent to Stanley.He is pleasant to all children. a video inspection snake is use What is limiting factor What caused the United States to adopt the policy of containment?a desire to prevent prosperity in GermanySoviet rejection of the Marshall Planthe spread of communism across Europethe spread of communism on several continents Which form of the verb beber correctly completes this conversation?Lucia: Qu ms tengo que hacer?Doctor: _________ ms agua.A. bebaB. bebenC. bebemosD. bebo How does the image of buddah tend to vary from statue to statue A coach surveyed a random sample of 200 college athletes about their height.A 2-column table with 4 rows. Column 1 is labeled Height (inches) with entries 60 to 64, 65 to 69, 70 to 74, 74 to 76. Column 2 is labeled Frequency with entries 14, 28, 53, 67.Which statements are correct about the data in the table? Check all that apply.A bar graph is an appropriate display.A pie chart is an appropriate display.A bar graph is not appropriate because the heights of the bars would be too different.A pie chart is not appropriate because the categories do not add to 100%.A bar graph is appropriate because the frequencies are given.Answer:A bar graph is an appropriate display.A pie chart is not appropriate because the categories do not add to 100%.A bar graph is appropriate because the frequencies are given. (philosophy)Pojman describes two arguments for moral objectivism. What are these arguments and how dothey differ? What was the goal of the Crusades?O A. To gain power for the MoorsO B. To push the Moors out of SpainO C. To retake Jerusalem from the MuslimsO D. To spread Catholicism to Asia Lines m and p are perpendicular. If the slope of line m is -3, what is the slope of line p? Si enfriamos mercurio de 100C. Calcular la cantidad de calor que se debe restar sabiendo que la masa de mercurio es de 1800gr Read the paragraph.[1] Studies have shown that kids who eat healthy food have more energy. [2] When students are more energized, they get better grades. [3] Still, half the Lincoln High students eat pizza at its lunchtime. [4] The school plans to start offering healthier options like salads and fruit as an alternative.Which sentence contains a pronoun-antecedent error?sentence 4sentence 3sentence 2sentence 1ANSWER: B Help! Which of the following strategies can reduce urban sprawl?A. Increasing the number of green beltsB. Decreasing the length of city blocksC. Creating expensive housing in the cityD. Eliminating high-rise homes and offices what's the ratio of 16 apple and 48carrots Exercise 6-10 Petty cash fund accounting LO P2 Palmona Co. establishes a $200 petty cash fund on January 1. On January 8, the fund shows $38 in cash along with receipts for the following expenditures: postage, $74; transportation-in, $29; delivery expenses, $16; and miscellaneous expenses, $43. Palmona uses the perpetual system in accounting for merchandise inventory. Prepare journal entries to (1) establish the fund on January 1, (2) reimburse it on January 8, and (3) both reimburse the fund and increase it to $450 on January 8, assuming no entry in part 2. Hint: Make two separate entries for part 3. He could understand it if you______it to him more clearly HELPASAPA circle with an arc length of ____ centimeters is intercepted by a central angle of 3pi/4 radians has a radius of ____ centimeters.1st Blank Options: 12pi, 4pi, 2pi2nd Blank Options: 3, 16, 24 Lainey is looking for a new apartment and her realtor keeps calling her with new listings. The calls only take a few minutes, but a few minutes here and there are really starting to add up. She's having trouble concentrating on her work. What should Lainey do? a) Tell her realtor she can only receive text messages O b) Limit the time spent on each call O c) Turn off her phone until she is on a break O di Call her realtor back when customers won't see her on the phone Define fear is fear itself What are some slang terms that you use on a regular basis? What do these terms mean? Where do these term come from?