SOLUTION: find the zeros of the function f(x)= x^3+x^2-20x. Thanks!

Algebra ->  Functions -> SOLUTION: find the zeros of the function f(x)= x^3+x^2-20x. Thanks!      Log On


   

Question 246656: find the zeros of the function f(x)= x^3+x^2-20x.
Thanks!
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
First factor the common factor:
f(x)=x^3+x^2 -20x
f(x)=x(x^2+x-20)

Now, factor the trinomial:
f(x)=x(x+5)(x-4)

Set each factor equal to 0.
x=0, x=-5, and x=4

You might even want to check this with a graphing calculator:
graph%28300%2C300%2C-6%2C6%2C-60%2C60%2C+x%5E3%2Bx%5E2-20x%29

Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamonte Springs Campus