SOLUTION: Solve the following polynomial equation. show your work. x^3+x^2+2x-4=0

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Solve the following polynomial equation. show your work. x^3+x^2+2x-4=0      Log On


   

Question 970668: Solve the following polynomial equation. show your work.
x^3+x^2+2x-4=0
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
The possible factors are +/- 1 +/-2 and +/-4
Let's try (x-1)
1 ;; 1 ;; 1 ;2 ;;-4
============1 ==2 ;=4
====== 1===2==4==0
(x-1) (x^2+2x+4)=0
One root is 1; the second does not factor (4ac is larger than b^2=see below)
The quadratic formula for the other 2
=[-2 +/- sqrt (4-16)]/2 ;; sqrt (-12)=sqrt (3)* sqrt (-4)= 2i (sqrt (3)
-1 +/- i* sqrt (3)
graph+%28300%2C300%2C-10%2C10%2C-10%2C10%2Cx%5E3%2Bx%5E2%2B2x-4%29
See a graph of a cubic equation with a root at x=1 and the y-intercept at (0.-4) consistent with the equation