How do you solve x3+4x2−x=0?

1 Answer
Gió
Jul 15, 2015

I found three solutions as follows:
x1=0
x2=−2+√5
x3=−2−√5

Explanation:

You can start collecting x to get:
x(x2+4x−1)=0
So you get:
x1=0
x2+4x−1=0 that can be solved using the Quadratic Formula as:
x2,3=−4±√16+42 which gives you two additional solutions:
x2=−4+√202=−2+√5
and:
x3=−4−√202=−2−√5

Where I used the fact that √20=√5⋅4=2√5

Related questions
See all questions in Comparing Methods for Solving Quadratics
Impact of this question
1636 views around the world
You can reuse this answer
Creative Commons License