Answer:
x = - 4 , x = 10
Explanation:
given
x² - 6x - 40 = 0 ← in standard form
consider the factors of the constant term (- 40) which sum to give the coefficient of the x- term (- 6)
the factors are - 10 and + 4
use these factors to split the x- term
x² + 4x - 10x - 40 = 0 ( factor the first/second and third/fourth terms )
x(x + 4) - 10(x + 4) = 0 ← factor out (x + 4) from each term
(x + 4)(x - 10) = 0 ← in factored form
equate each factor to zero and solve for x
x + 4 = 0 ( subtract 4 from both sides )
x = - 4
x - 10 = 0 ( add 10 to both sides )
x = 10
the solutions are x = - 4 , x = 10