What are the roots of y^3 + y^2 - 16 = 0

Question

The rational roots test doesn't give any roots.

 

I'm stuck.

Answer 1

First by trial and error find out where the LHS changes sign at y=2 LHS=8+4-16=-4 at y=3 LHS=27+9-16=20 so there is a real root between 2 and 3.

Next you can plot the LHS as a function of y between 2 and 3 and you should be able to estimate the root. I got 2.23. There may be complex roots also.

 

Jim