SOLUTION: Hello,I'd like help on this question Factor ​f(x)=4x^3+11x^2-40x+25 into linear factors given that −5 is a zero of​ f(x). Thank you

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: Hello,I'd like help on this question Factor ​f(x)=4x^3+11x^2-40x+25 into linear factors given that −5 is a zero of​ f(x). Thank you      Log On


   

Question 1142729: Hello,I'd like help on this question
Factor ​f(x)=4x^3+11x^2-40x+25 into linear factors given that −5 is a zero of​ f(x).
Thank you
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
​f(x)=4x^3+11x^2-40x+25 into linear factors given that −5 is a zero 


-5   |   4   11   -40   25
     |
     |      -20    45   -25
     ---------------------------------
         4  -9    5     0

f%28x%29=%28x%2B5%29%284x%5E2-9x%2B5%29

Zeros of the quadratic factor:
%289%2B-+sqrt%2881-4%2A4%2A5%29%29%2F%282%2A4%29
%289%2B-+1%29%2F8
system%281%2C+and%2C+5%2F4%29

Try testing for 1 as a zero.
1   |   4    -9    5
     |
     |        4    -5
     |------------------------
        4    -5    0

This means 4x-5 is also a linear factor.

highlight%28f%28x%29=%28x%2B5%29%28x-1%29%284x-5%29%29