Solve
x2 + 2x – 15 = 0

x = - 5, x = 3

Step-by-step explanation:

Given

x² + 2x - 15 = 0

Consider the factors of the constant term (- 15) which sum to give the coefficient of the x- term (+ 2)

The factors are + 5 and - 3 , since

5 × - 3 = - 15 and 5 - 3 = + 2, so

x² + 2x - 15 = 0

(x + 5)(x - 3) = 0 ← in factored form

Equate each factor to zero and solve for x

x + 5 = 0 ⇒ x = - 5

x - 3 = 0 ⇒ x = 3

option 3 . (5x + 1) - (-10x + 6)

step-by-step explanation:

option 1 :

(4x + 3) + (-9x + 4)

or 4x+3 -9x + 4

or -5x + 7

option 2

(x - 2) - (6x - 9)

or x-2-6x + 9

or -5x + 7

option 3

(5x+ + 6)

or 5x + 1 + 10x -6

or 15x -5

option 4

-4x+2x+7-3x

-7x + 2x + 7

-5x + 7

hence only option 3 did   not satisfy the given simplify expression.