Question

Multiply the polynomials: (x – 4)(x2 + 2x – 5)

Question 16 options:

A)

x3 + 6x2+ 3x – 20

B)

x3 + 6x2 + 3x + 20

C)

x3 – 2x2 – 13x – 20

D)

x3 – 2x2 – 13x + 20
Question 17 (5 points)
Subtract: (4x3 + 9xy + 8y) – (3x3 + 5xy – 8y)
Question 17 options:

A)

7x3 + 14xy

B)

x3 + 4xy

C)

7x3 + 14xy + 16y

D)

x3 + 4xy + 16y
Question 18 (5 points)
What are the real solutions to the equation 5x2 + 29x + 20 = 0?
Question 18 options:

A)

x = –5, x = 4∕5

B)

x = –4∕5, x = 5

C)

x = 4∕5, x = 5

Answer 1

Explanation:

Hey there!

Given;

`= (x - 4)( {x}^(2) + 2x - 5)`

`= x( {x}^(2) + 2x - 5) - 4( {x}^(2) + 2x - 5)`

`= {x}^(3) + 2 {x}^(2) - 5x - 4 {x}^(2) - 8x + 20`

`= {x}^(3) - 2 {x}^(2) - 13x + 20`

Therefore, Option D is correct answer.

Q.no.

Given;

`=( 4 {x}^(3) + 9xy + 8y) - (3 {x}^(3) + 5xy - 8y)`

`= 4 {x}^(3) + 9xy + 8y - 3 {x}^(3) - 5xy + 8y`

`= {x}^(3) + 4xy + 16y`

Therefore, answer is Option D.

Qno.

Given;

`5 {x}^(2) + 29x + 20 = 0`

`5 {x}^(2) + (25 + 4)x + 20 = 0`

`5 {x}^(2) + 25x + 4x + 20 = 0`

`5x(x + 5) + 4(x + 5) = 0`

(5x + 4)(x + 5) =0

Either (5x+4)= 0,

5x = -4

X = -4/5

Or, X+5 = 0

X = -5.

Therefore, X= -5, -4/5.

Hope it helps....