For what values of x is x2 + 2x = 24 true?

x = - 6, x = 4

Step-by-step explanation:

Given

x² + 2x = 24 ( subtract 24 from both sides )

x² + 2x - 24 = 0

To factorise the quadratic

Consider the factors of the constant term (- 24) which sum to give the coefficient of the x- term (+ 2)

The factors are + 6 and - 4, since

6 × - 4 = - 24 and 6 - 4 = + 2, hence

(x + 6)(x - 4) = 0

Equate each factor to zero and solve for x

x + 6 = 0 ⇒ x = - 6

x - 4 = 0 ⇒ x = 4

- 2 + 10x³ - 21x² + 19x - 4

step-by-step explanation:

each term in the second factor is multiplied by each term in the first factor

x²(- 2x² + 4x - 1) - 3x(- 2x² + 4x - 1) + 4(- 2x² + 4x - 1) ← distribute

= - 2 + 4x³ - x² + 6x³ - 12x² + 3x -8x² + 16x - 4

collect like terms

= - 2 + 10x³ - 21x² + 19x - 4 ← in standard form

the answer will be b x² +x-1

step-by-step explanation: