Question

Solve n3 + 2n2 - 15n = 0 by factoring.

Answer 1

n³ - 2n² - 15n = 0

"n"

n (n² + 2n - 15) = 0

n = 0

n² + 2n - 15 = 0

Δ = (2)² - 4(1)(-15)
Δ = 4 + 60 = 64

n' = (-2+8) / 2 = 6/2 =3
n'' = (-2-8) / 2 = -10/2 = -5

Solution:

S {-5 , 0 , 3 }

Answer 2

n^3+2n^2-15n=0

n(n^2+2n-15)=0

n(n^2+5n-3n-15)=0

n(n(n+5)-3(n+5))=0

n(n-3)(n+5)=0

n={-5, 0, 3}