Question

HELP me please !! I really need it

Answer 1

D. -4, 5

Explanation:

x² - x - 20 factorised = (x - 5) (x + 4)

In order to get the answers, you have to make each bracket equal zero.

(x - 5) = x = 5

(x + 4) = x = -4

The crucial numbers are -4 and 5.

Hope this helps!

Answer 2

D

Explanation:

To find the critical values , that is the zeros

Solve the quadratic

x² - x - 20 = 0 ← in standard form

Consider the factors of the constant term (- 20) which sum to give the coefficient of the x- term (- 1)

The factors are - 5 and + 4, since

- 5 × 4 = - 20 and - 5 + 4 = - 1, hence

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

Equate each factor to zero and solve for x

x - 5 = 0 ⇒ x = 5

x + 4 = 0 ⇒ x = - 4

Thus the critical values are - 4, 5 → D