1. thực hiện phép nhân
a) (2x-1)(x-8)
b) (x^2-3)(2x+4)
c) (2x-1)x+x^2-2(x-3)
d) x(2x-6).(-3x)+9x(x-1)
e) 2x(x^2-3x)-(x+1)(x^2-2)
f)3x(x-1)+x^2(x-2)+3(x-1)(x+1)

9514 1404 393

Answer:

  (a)  42.3°

Step-by-step explanation:

Side 'a' is the shortest of three unequal sides, so angle A will be the smallest angle in the triangle. Its measure can be found from the Law of Cosines.

  a² = b² +c² -2bc·cos(A)

  cos(A) = (b² +c² -a²)/(2bc) = (21² +25² -17²)/(2·21·25) = 777/1050

  A = arccos(777/1050) ≈ 42.3°

The measure of angle A is about 42.3°.

_____

Additional comment

The smallest angle in a triangle can never be greater than 60°. This lets you eliminate choices that exceed that value.

Answer:

 (a)  42.3°

Step-by-step explanation:

Answer:

12-4y=4-12y

8y=-8

y=-1

Answer:

y= 0.8

Step-by-step explanation

4(3−y) = 6−2(1−3y)

12−4y = 6−2(1−3y)

12−4y = 6−2+6y

12−4y = 4+6y

  12   =  4+10y

     8 = 10y

  0.8 = y

This is correct i just took the test. I hope this helps :)

Step-by-step explanation:

x will be raised to the power of 1 if there's no power associatiated to it. Thus, you will have to flip the numbers to turn it into exponential form

Answer:

root3

Step-by-step explanation:

multiply the numerator and denominator by the root of 3

3root2×root3/root3×root3

3root6/3

note root3×root3=3

the 3 up will divide the 3 down

and that lives u with the answer root2

sorry currently won't have a way of writing the roots thats y am using words

Answer:

44/3 degrees

Step-by-step explanation:

Angle CBD = 180 - (64 + 72) = 44

Angle ADB = 44/3 (Since of the ratio)

X - 3/8 = 13/2

Add 3/8 to both sides:

X = 13/2 + 3/8

Rewrite 13/2 to have 8 as the denominator:

13/2 x 4 = 52/8

X = 52/8 + 3/8

X = 55/8

Answer:

55/8

Step-by-step explanation:

Add 3/8 to both sides

X - 3/8 = 13/2

X = 13/2 + 3/8

make sure the denominators are equal so we can add. so multiply 4/4 by 13/2 and that equals 52/8

X = 52/8+3/8

X= 55/8

The side of the square is 6.2 cm

A square is a quadrilateral with four equal sides.

Characteristics of a square includes:

• The diagonals bisect each other at 90°.

• Opposite sides parallel and of equal length

• The four angles of a square are equal.

Area of a square = length of a side²

37.8225cm² = length of a side²

To determine the length of a side, find the square root of 37.8225cm²

√ 37.8225cm² = 6.15cm

To round off to one decimal place, look at the second number after the decimal (the hundredth). If the number is greater or equal to 5, add 1 to the tenth figure. If this is not the case, add zero

The hundredth number is 5, so one would be added to one. the number then becomes 6.2cm

Learn more on how to determine the side length of a square here : https://brainly.com/question/10646504?referrer=searchResults

Answer:

x=11

Step-by-step explanation:

51-x-5*19= -5x

51-5*19= -4x

4x=5*19-51

4x=95-51

4x=44

x=11

Step-by-step explanation:

let x year ago son age was 5 time his father age.

age of son before x year = 19-x

age of father before x year = 51-x

NOW

according to the question

5(19-x) =51-x

95-5x =51-x

95-51 = -X-5x

44 = 4x

x=11

so your ans is 11years ago

Answer:

Roots is a fancy word for zero, which is also another fancy word for the x intercept.

You can factor a quad or use the quadratic equation to get zeros.

In this case, its non-factorable. So you gotta use the quadratic.

Using the quadratic equation you get : x = -2 ± √-1 (√5),

which can be rewritten as x = -2 ± i(√5)

Function was : x^2 + 4x + 9

For quad, I identified the following:

A = 1

B = 4

C = 9

I also added a picture of the formula in the attached.

Answer:

f (x) = x2 - 3x + 2

Step-by-step explanation:

Answer:

f(x)=-3x+2

Step-by-step explanation:

The first one is a quadtratic function because it is in quadtratic form.

The second one is also not linear because it looks like a squiggly line. Sorry I forgot what they are called but I know it is not linear.

That leaves the last one is is linear and should be going down because there is a negative in front of the coefficient. It also has so exponent to prove why it is linear even further.

Hope this helps!

Answer:

6 mm and 9 mm are the dimensions of the piece of plastic.

Step-by-step explanation:

Keep in mind the formulas for the area and perimeter of a rectangle:

A = lw

P = 2 (l + w)

List the factors of 54:

1, 2, 3, 6, 9, 18, 27, 54

POSSIBLE DIMENSIONS of the piece of plastic:

1 mm and 54 mm:

Area - 54 mm^2

Perimeter - 110 mm

2 mm and 27 mm

Area - 54 mm^2

Perimeter - 58 mm

3 mm and 18 mm

Area - 54 mm^2

Perimeter - 42 mm

6 mm and 9 mm

Area - 54 mm^2

Perimeter - 30 mm

The rectangular piece of plastic with the dimensions 6mm and 9 mm corresponds with the area and perimeter of the piece of plastic mentioned. So these are the correct dimensions.

Hope this helps!

Pages read by Arnold in 7 minutes = 3 pages

Pages read by Arnold in 1 minutes

= 3/7 pages

= 6/14 pages

Pages read by Brenda in 14 minutes = 8 pages

Pages read by Brenda in 1 minutes = 8/14 pages

(6/14) < (8/14)

So, speed of Arnold < speed of Brenda.

So, Brenda reads faster.

Answer:

c = 85 yd

Step-by-step explanation:

Using Pythagoras' identity in the right triangle.

The square on the hypotenuse is equal to the sum of the squares on the other 2 sides , that is

c² = 77² + 36² = 5929 + 1296 = 7225 ( take square root of both sides )

c = [tex]\sqrt{7225}[/tex] = 85

Answer:

[tex]85yd[/tex]

Step-by-step explanation:

According to PYTHAGORAS Theorem,

[tex] {c}^{2} = {77}^{2} + {36}^{2} \\ {c}^{2} = 5929 + 1296 \\ {c}^{2} = 7225 \\ c = \sqrt{7225} \\ c= 85yd[/tex]

Answer: Circumference of circle = 27.004 inches

              Area of circle = 58.0586 inches²

Step-by-step explanation:

Diameter of circle = 8.6 inches

Pi ([tex]\pi[/tex]) = 3.14

Circumference of circle (With diameter) = [tex]\pi \\[/tex]d ([tex]\pi[/tex]×diameter)

                                                                = 3.14 × 8.6

                                                                = 27.004 inches

Area of circle (With diameter) = [tex]\pi[/tex][tex]d^{2}[/tex]/4

                                                 = 3.14 × 8.6 × 8.6 / 4

                                                 = 3.14 × 73.96 / 4

                                                 = 58.0586 inches²

Answer: C : 11

Step-by-step explanation:

Answer:

[tex]x = \frac{2 \sqrt{3} }{3} [/tex]

[tex]y = 1[/tex]

Step-by-step explanation:

30, 60, 90 triangle

104 ft^2

Explanation:

The surface areaa of a rectangular prism is given by the formula:

2 (lw + hl + hw)

l = length

w = width

h = height

Substitute the formula with the givsn dimensions:

2 ([6 x 2] + [5 x 6] + [5 x 2])

= 2 (12 + 30 + 10)

2 (52)

= 104

So the SA is 104 square feet or ft^2

Hope this helps!

Answer:

3b (3a - 4b)

Step-by-step explanation:

Answer:

C

Step-by-step explanation:

9ab - 12b² ← factor out 3b from each term

= 3b(3a - 4b) → C

Answer:

B

Step-by-step explanation:

half × base × height

height × length

Answer: B

Step-by-step explanation:

Triangle)

25 - 7 = 18

[tex]A=\frac{1}{2}(b)(h)\\A=\frac{1}{2}(18)(17)\\A=153cm^2[/tex]

Rectangle)

[tex]A=b(h)\\A=7(17) = 119cm^2[/tex]

Total)

[tex]153+119=272 cm^2[/tex]

Answer:

7 cannot be achieved

-1 + 6 = 5

-3 + 4 = 1

-5 + 2 = -3

as you can see, no combinations can form seven

Step-by-step explanation:

-6>t-(-13)

= -6>t+13

= -6-13>t

= -19>t

= t<-19

Answer:

t < - 19

Step-by-step explanation:

Given

- 6 > t - (- 13) , that is

- 6 > t + 13 ( subtract 13 from both sides )

- 19 > t , then

t < - 19

Answer:

hes going 10 miles an hour,

Step-by-step explanation:

if it took you 3.5 hrs and you went 35 miles, you can do 35/3.5=10, which is 10 miles an hour

Answer:

10 miles per hour

Step-by-step explanation:

We know that distance = rate * time

35 miles = rate * 3.5 hours

Divide each side by 3.5 hours

35 miles / 3.5 hours = rate

10 miles per hour = rate

Answer:

The angles that are congruent to 4 are: 3, 8, and 7.

3 and 4 are vertical angles, 8 and 3 are opposite interior angles, 8 and 7 are vertical angles.

Hope this helps!

Answer:

your slope would be 4.5.... so go up 4 and to the right 5. the y-intercept is 650 so that is where your line would start instead of at 0... hope this helped :)

Step-by-step explanation:

The exponential function gotten from the table is given by y = 650(1.045)ˣ

An exponential function is in the form:

y = abˣ

where y, x are variables, a is the initial value of y and b is the multipliers.

Let y represent the bacteria population after x hours.

The class started out with 650 bacteria cells.

Growth rate = 4.5%

The exponential function gotten from the table is given by y = 650(1.045)ˣ

After 30 hours:

Find out more on exponential function at: https://brainly.com/question/12940982

Answer:

4

Step-by-step explanation:

Let the number be x.

According to the question,

[tex]\dashrightarrow \sf { \dfrac{1}{4}x - \dfrac{1}{5}x= 8 + 10 } \\[/tex]

[tex]\dashrightarrow \sf { \dfrac{5x + 4x}{2}= 18 } \\[/tex]

[tex]\dashrightarrow \sf { \dfrac{9x}{2}= 18 } \\[/tex]

[tex]\dashrightarrow \sf { 9x = 18 \times 2 } \\[/tex]

[tex]\dashrightarrow \sf { 9x = 36 } \\[/tex]

[tex]\dashrightarrow \sf { x =\cancel{ \dfrac{36}{9} }} \\[/tex]

[tex]\dashrightarrow \underline{\boxed{\pmb { \frak {x = 4 }}}} \\[/tex]

The number is 4.

Answer:

[tex]x = 34^\circ[/tex]

Step-by-step explanation:

Note that ∠TSU and ∠PSR are vertical angles. Hence:

[tex]m\angle TSU = m\angle PSR[/tex]

∠PSR is the sum of ∠PSQ and ∠QSR. Hence:

[tex]\displaystyle m\angle TSU = m\angle PSQ + m\angle QSR[/tex]

We know that ∠TSU measures 4x and ∠QSR measures 3x. Thus:

[tex](4x) = m\angle PSQ + (3x)[/tex]

Solve for ∠PSQ:

[tex]m\angle PSQ = x[/tex]

Next, ∠PQS and ∠RQS form a linear pair. Thus:

[tex]m\angle PQS + m\angle RQS = 180^\circ[/tex]

∠RQS measures 68°. Thus:

[tex]m\angle PQS +(68^\circ) = 180^\circ[/tex]

Solve for ∠PQS:

[tex]m\angle PQS = 112^\circ[/tex]

The interior angles of a triangle must total 180°. So, for ΔPQS:

[tex]\displaystyle m\angle SPQ + m\angle PQS + m\angle PSQ = 180^\circ[/tex]

Substitute in the known values:

[tex](x) + (112^\circ) + (x) = 180^\circ[/tex]

Simplify:

[tex]2x = 68^\circ[/tex]

And divide. Hence:

[tex]x = 34^\circ[/tex]

Answer:

y = 3x+6

Step-by-step explanation:

refer to the picture

Answer:

y = 3x + 6

Step-by-step explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

y = 3x + 2 ← is in slope- intercept form

with slope m = 3

Parallel lines have equal slopes, so slope of parallel line is 3

Expressing the equation in point- slope form with m = 3 , (x₁, y₁ ) = (1, 9)

y - 9 = 3(x - 1)

y - 9 = 3x - 3 ( add 9 to both sides )

y = 3x + 6 ← in slope- intercept form

Answer:

(3.5, - 3.5)

Step-by-step explanation:

Using the Midpoint theorem, we have

x=(9-2)/2=7/2=3.5

y=(-8+1)/2=-7/2=-3.5