Turn the equation into factored form Y=x^3+3x^3-6x-8

Mathematics · High School · Tue Nov 03 2020

Answered on

We have, Y=x^3+3x^3-6x-8

By trial and error
let f(x)=x^3+3x^2−6x−8
let x=−1
so f(−1)= (-1)^3 + 3(-1)^2 -6(-1) -8

−1+3+6−8=0
so (x+1) is a factor
 

so,
x^3+3x^2−6x−8/x+1 = x^2+2x−8


Now, we have to factorise  x^2+2x−8
x^2+2x−8 =0

 x^2+4x- 2x−8 =0

x(x+4) -2(x+4) -0

(x−2)(x+4) = 0
Hence, factors of x^3+3x^2−6x−8 is (x+1)(x−2)(x+4)


x^3+3x^2−6x−8=(x+1)(x−2)(x+4)