what is the additive identity of rational number​

Answer:

see explanation

Step-by-step explanation:

Given

AB + BC = 31

AB - BC = 17

Add the 2 equations

2AB = 48 ( divide both sides by 2 )

AB = 24

Substitute AB = 24 into the first equation

24 + BC = 31 ( subtract 24 from both sides )

BC = 7

Using Pythagoras' identity to find the hypotenuse AC

AC² = AB² + BC² = 24² + 7² = 576 + 49 = 625 ( take square root of both sides )

AC = [tex]\sqrt{625}[/tex] = 25

Then

sinA = [tex]\frac{opposite}{hypotenuse}[/tex] = [tex]\frac{BC}{AC}[/tex] = [tex]\frac{7}{25}[/tex]

cosA = [tex]\frac{adjacent}{hypotenuse}[/tex] = [tex]\frac{AB}{AC}[/tex] = [tex]\frac{24}{25}[/tex]

sinC = [tex]\frac{AB}{AC}[/tex] = [tex]\frac{24}{25}[/tex]

cosC = [tex]\frac{BC}{AC}[/tex] = [tex]\frac{7}{25}[/tex]

Answer:

B

Step-by-step explanation:

n is the number of litres.

if you substitute 1 for 'n' then you will get :

C = 8 + 1.5(1)

C = $9.5

$9.50 for every litre

Answer:

C is correct

Step-by-step explanation:

The $8 charge is only once regardless of how many liters are ordered, so only answer C works.

Answer:

Step-by-step explanation:

Let the regular price is x, then:

Answer:

DE = 11

Step-by-step explanation:

DF = DF +EF

4x+2 = x+7 + 7

Combine like terms

4x+2 = x+14

Subtract x from each side

4x+2-x = x+14-x

3x+2 = 14

Subtract 2 from each side

3x+2-2 =14-2

3x=12

Divide by 3

3x/3 = 12/3

x = 4

DE = x+7 = 4+7 =11

Answer:

DE is 11

Step-by-step explanation:

[tex]DE = DF - EF \\ DE = (4x + 2) - 7 \\DE = 4x - 5 [/tex]

But for x:

[tex]4x + 2 = (x + 7) + 7 \\ 4x + 2 = x + 14 \\ 3x = 12 \\ x = 4[/tex]

Therefore:

[tex]DE = (4 \times 4) - 5 \\ = 16 - 5 \\ = 11[/tex]

Answer:

0.7

Step-by-step explanation:

7/11 = 0.63636363

7/9 = 0.777777778

so a decimal between them will be, 7/10 = 0.7

Answer:

let,

√x-5=ky

x=30 when y=2

√30-5=2k

or, k=(√30-5)/2

now, when y=8

√x-5=8×(√30-5)/2

or, √x-5=4√30-20

or, √x=4√30-15

or, x=(4√30-15)²

or, x=47.73..

Answer:

Step-by-step explanation:

I can't believe I'm doing this for 5 points, but ok!

For the first 3, we are going to multiply to find the value of that 3 x 3 matrix by picking up the first 2 columns and plopping them down at the end and then multiplying through using the rules for multiplying matrices:

[tex]\left[\begin{array}{ccccc}7&4&6&7&4\\-4&8&9&-4&8\\1&8&7&1&8\end{array}\right][/tex]  and from there find the sum of the products of the main axes minus the sum of the products of the minor axes, as follows (I'm not going to state the process in the next 2 problems, so make sure you follow it here. This is called the determinate. The determinate is what you get when you evaluate or find the value of a matrix. Just so you know):

[tex](7*8*7)+(4*9*1)+(6*-4*8)-[(1*8*6)+(8*9*7)+(7*-4*4)][/tex] which gives us:

392 + 36 - 192 - [48 + 504 - 112] which simplifies to

236 - 440 which is -204

On to the second one:

[tex]\left[\begin{array}{ccccc}-8&-4&-1&-8&-4\\1&7&-3&1&7\\8&9&9&8&9\end{array}\right][/tex] and multiplying gives us

[tex](-8*7*9)+(-4*-3*8)+(-1*1*9)-[(8*7*-1)+(9*-3*-8)+(9*1*-4)][/tex] which gives us:

-504 + 96 - 9 - [-56 + 216 - 36] which simplifies to

-417 - 124 which is -541, choice c.

Now for the third one:

[tex]\left[\begin{array}{ccccc}-2&-2&-5&-2&-2\\2&7&-3&2&7\\8&9&9&8&9\end{array}\right][/tex] and multiplying gives us

[tex](-2*7*9)+(-2*-3*8)+(-5*2*9)-[(8*7*-5)+(9*-3*-2)+(9*2*-2)][/tex] which gives us:

[tex]-126+48-90-[-280+54-36][/tex] which simplifies to

-168 - (-262) which is 94, choice c again.

Now for the last one. I'll show you the set up for the matrix equation; I solved it using the inverse matrix. So I'll also show you the inverse and how I found it.

[tex]\left[\begin{array}{cc}-4&-5&\\-6&-8\\\end{array}\right][/tex] [tex]\left[\begin{array}{c}x\\y\\\end{array}\right][/tex] = [tex]\left[\begin{array}{c}-5\\-2\\\end{array}\right][/tex] and I found the inverse of the 2 x 2 matrix on the left.

Find the inverse by:

* finding the determinate

* putting the determinate under a 1

* multiply that by the "mixed up matrix (you'll see...)

First things first, the determinate:

|A| = (-4*-8) - (-6*-5) which simplifies to

|A| = 32 - 30 so

|A| = 2; now put that under a 1 and multiply it by the mixed up matrix. The mixed up matrix is shown in the next step:

[tex]\frac{1}{2}\left[\begin{array}{cc}-8&5\\6&-4\end{array}\right][/tex]  (to get the mixed up matrix, swap the positions of the numbers on the main axis and then change the signs of the numbers on the minor axis). Now we multiply in the 1/2 to get the inverse:

[tex]\left[\begin{array}{cc}-4&\frac{5}{2}\\3&-2\\\end{array}\right][/tex] Multiply that inverse by both sides of the equation. This inverse "undoes" the matrix that's already there (like dividing the matrix that's already there by itself) which leaves us with just the matrix of x and y. Multiply the inverse matrix by the solution matrix:

[tex]\left[\begin{array}{c}x&y\end{array}\right] =\left[\begin{array}{cc}-4&\frac{5}{2} \\3&-2\end{array}\right] *\left[\begin{array}{c}-5&-2\\\end{array}\right][/tex] and that right side multiplies out to

x = 20 - 5 which is

x = 15 and

y = -15 + 4 which is

y = -11

(It works, I checked it)

Answer:

-3/4

Step-by-step explanation:

First, let's convert the mixed numbers into improper fractions in an effort to make this problem easier to solve.

-2 1/2 as a mixed number is -5/2 and -1 3/4 as a mixed number is -7/4.

Our problem is now -5/2 - (-7/4).

We still can't solve this because the two fractions do not share a common denominator. 4 can serve as one, so -5/2 with a denominator of 4 would be -10/4.

The problem is now -10/4 - (-7/4).

Two negatives make a positive so the problem can be rewritten as -10/4 + 7/4. The final answer is -3/4.

Answer:

A

Step-by-step explanation:

lm‎ao this problem is b‎u‎l‎ls‎h‎‎‎i‎t because the actual answer would be [2, 2] U (7, infty) but thats literally not there, so ig the closest one would be [2, infty) which is A

if it was asking for the domain on the other hand, then it would be B lm‎ao

but I would go with A

Answer:

y = -x + 4

Step-by-step explanation:

(x₁,y₁)= (5, - 1)    & (x₂,y₂)= (2 , 2)

Slope = [tex]\frac{y_{2}-y_{1}}{x_{2}-x_{1}}[/tex]

         [tex]\frac{2-[-1]}{2-5}\\\\=\frac{2+1}{-3}\\\\=\frac{3}{-3}\\\\= -1[/tex]

m = -1

Equation of the line y - y₁ = m(x - x₁)

y  - [-1] = (-1)*(x - 5)

y + 1 = -x + 5      {-1 is distributed}

y = -x + 5 - 1

y = -x + 4

Answer:

How can postulates and theorems relating to similar and congruent triangles be used to write a proof? If the three sets of corresponding sides of two triangles are in proportion, the triangles are similar. ... If the three sets of corresponding sides of two triangles are in proportion, the triangles are similar.

Step-by-step explanation:

Hope this helps :D good luck!!

Answer:

h = 504, k = 65, t = -1

Step-by-step explanation:

56 = h/9

h = 56 x 9

h = 504

k/5 - 10 = 3

k/5 = 3 + 10

k/5 = 13

k = 13 x 5

k = 65

3t + 5 = 2

3t = 2 - 5

3t = -3

t = -3/3

t = -1

Use the formula given. R is half the diameter

R = 14/2 = 7 inches.

Area = 3.14 x 7^2

Area = 153.86 inches^2

Answer:

Does the answer help you?

Answer:

-3(2x-4) or -6x+12

Step-by-step explanation:

Area is H*W

theres no value for x so that would be it, unless there is then all you do is plug that into the answer I put.

Part (a)

Consecutive odd integers are integers that odd and they follow one right after another. If x is odd, then x+2 is the next odd integer

For example, if x = 7, then x+2 = 9 is right after.

========================================================

Part (b)

The consecutive odd integers we're dealing with are x and x+2.

Their squares are x^2 and (x+2)^2, and these squares add to 394.

========================================================

Part (c)

We'll solve the equation we just set up.

x^2 + (x+2)^2 = 394

x^2 + x^2 + 4x + 4 = 394

2x^2+4x+4-394 = 0

2x^2+4x-390 = 0

2(x^2 + 2x - 195) = 0

x^2 + 2x - 195 = 0

You could factor this, but the quadratic formula avoids trial and error.

Use a = 1, b = 2, c = -195 in the quadratic formula.

[tex]x = \frac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\x = \frac{-(2)\pm\sqrt{(2)^2-4(1)(-195)}}{2(1)}\\\\x = \frac{-2\pm\sqrt{784}}{2}\\\\x = \frac{-2\pm28}{2}\\\\x = \frac{-2+28}{2} \ \text{ or } \ x = \frac{-2-28}{2}\\\\x = \frac{26}{2} \ \text{ or } \ x = \frac{-30}{2}\\\\x = 13 \ \text{ or } \ x = -15\\\\[/tex]

If x = 13, then x+2 = 13+2 = 15

Then note how x^2 + (x+2)^2 = 13^2 + 15^2 = 169 + 225 = 394

Or we could have x = -15 which leads to x+2 = -15+2 = -13

So, x^2 + (x+2)^2 = (-15)^2 + (-13)^2 = 225 + 169 = 394

We get the same thing either way.

Answer:

All of them except 12:25 simply to 2:5. So 12:25 is the odd one out.

Answer:

[tex] {(x - y)}^{2} \\ = (x - y)(x - y)[/tex]

open the brackets:

[tex] = ( {x}^{2} - xy - xy + {y}^{2} ) \\ = {x}^{2} - 2xy + {y}^{2} [/tex]

Step-by-step explanation:

3(6+b)+2b+1

18+3b+2b+1

5b+19

Answer:

-8x^3 + 64x^2 - 24x

Step-by-step explanation:

To distribute, we must multiple -8x to each term:

-8x(x^2) - 8x(-8x) - 8x(3)

-8x^3 + 64x^2 - 24x

Step-by-step explanation:

[tex] - 8x( {x}^{2} - 8x + 3) \\ = ( - 8x \times {x}^{2}) - ( - 8x \times 8x) + ( - 8x \times 3) \\ = - 8 {x}^{3} + 64 {x}^{2} - 24x[/tex]

distribute -8x to each term in the perenthesis i.e. multiply each term by -8x

Answer:n=6

Step-by-step explanation:

[tex]\\ \sf\longmapsto q+12-2(q-22)>0[/tex]

[tex]\\ \sf\longmapsto q+12-2q+44>0[/tex]

[tex]\\ \sf\longmapsto q-2q+12+44>0[/tex]

[tex]\\ \sf\longmapsto -q+56>0[/tex]

[tex]\\ \sf\longmapsto -q>-56[/tex]

[tex]\\ \sf\longmapsto q<56[/tex]

Answer:

there is a 25% decrease in books being read

Answer:

Step-by-step explanation:

Well I can show you by example. Try 28

a = 2

b = 8

2 - 2*8 = 2 - 16 = -14

- 14 is divisible by 7. You get - 2.

That means that 28 is also divisible by 8

We'll try one more. Try 56

a = 5

b = 6

5 - 2*6 = 5 - 12 = - 7

- 7 is divisible by 7 so 56 must be as well. What I'm wondering is if the rule in some form works for 735 and if it does how?

a = 73

b = 5

73 - 10 = 63

63 is divisible by 7 (giving 9)

so 10*73 + b is divisible by 7.

Try something a bit harder.

115444

a = 11544

b = 4

a - 2*4

11544 - 8

11536 / 7

1648 which works perfectly.

115444 is divisible by 28 which is a multiple of 7

Really amazing! Thanks for posting.

Answer:

Hello

Step-by-step explanation:

[tex]y=2x^2-12x+19\\=2(x^2-6x)+19\\=2(x^2-2*3*x+9)+19-18\\=2(x-3)^2+1\\\\Vertex\ is\ (3,1)\\\\Axis\ of\ symmetry\ is\ x=3\\\\y-intercept\ is \\\\y=2(0-3)^2+1=19\\[/tex]

Answer:

Step-by-step explanation:

2) Cost Price = CP = $ 35

Tax = $ 3.29

Tax percent = [tex]\frac{tax}{CP}*100[/tex]

                    [tex]= \frac{3.29}{35}*100\\\\[/tex]

                    = 9.4 %

Total amount paid by Ian = CP + tax = 35 + 3.29

                                          = $ 38.29

3) Price of the order = $ 56.50

Shipping cost % = 3 % = 0.03

Shipping cost = price of the order * shipping cost %

                       =  56.5 * 0.03

                       =  1.695

                       = $ 1.70

Total cost = Price of the order + Shipping cost

                = 56.5 + 1.70

                = $ 58.20

4) Bill amount = $ 26

Tip % = 18%

Tip amount = Tip % * bill amount

                   [tex]= \frac{18}{100}*26\\[/tex]

                   = $ 4.68

5) commission% = 3.5 %

Commission amount = commission% * Sales

                                   [tex]= \frac{3.5}{100}*50000[/tex]

                                  = $ 1750

Base salary for a week  = $400

Base salary  for two weeks = 400 * 2 = $ 800

Emmett's earning for this two weeks period = Base salary for two weeks + commission

= 800 + 1750

= $ 2550

6) Tax % = 10.25 %

Purchase amount = $ 310.50

Tax = Tax% * Purchase amount

      [tex]= \frac{10.25}{100}*310.50[/tex]

      = $ 31.83

Total = Purchase amount  + Tax

         = 310.50+ 31.83

         = $ 342.33

Answer:

162

Step-by-step explanation:

because this is a parallelogram :

m<2 = m<4 so

4x - 22 = 3x - 12

4x - 3x = 22 - 12

x = 10 replace x with 10 in the equation for m<4

3x - 12 is 30 - 12 = 18

m<4 and m<1 are supplementary and their sum is equal to 180

m<4 + m<1 = 180

m<1 = 180 - 18

m<1 = 162

Answer:

3

Step-by-step explanation:

7-4