Question

For what values of x is x2-36=5x true?
0 -9 and 4
04 and 9
4 and -9
09 and 4

Answer 1

x = - 4 and x = 9

Explanation:

Given

x² - 36 = 5x ( subtract 5x from both sides )

x² - 5x - 36 = 0

Consider the factors of the constant term (- 36) which sum to give the coefficient of the x- term (- 5)

The factors are - 9 and + 4, since

- 9 × 4 = - 36 and - 9 + 4 = - 5, thus

(x - 9)(x + 4) = 0

Equate each factor to zero and solve for x

x - 9 = 0 ⇒ x = 9

x + 4 = 0 ⇒ x = - 4