Factor: a² + 9a+20
A
(a-4)(-5)
B (a+2)(a +10)
C (-2)(a-10)
D (a+4)(a +5)

Using the simple method of quadratic expression:

we find two  numbers(the first and last word) that when we multiply is the same as when we add them together.

a²+9a+20

a²+4a+5a+20

The answer is D

a(a+4)+5(a+4)

(a+4)(a+5)

x ∈ R

Step-by-step explanation:

4x+x+4=8x−3x+4

Combine 4x and x to get 5x.

5x+4=8x−3x+4

Combine 8x and −3x to get 5x.

5x+4=5x+4

Subtract 5x from both sides.

5x+4−5x=4

Combine 5x and −5x to get 0.

4=4

Compare 4 and 4.

True

This is true for any x.

x ∈ R