Find all real and complex zeros of h(x)

[FrugalIntelle]

Homework Statement

It's asking me to find all the real and complex zeros of the function x^3 + 2x^2 - 16.

Homework Equations

The Attempt at a Solution

I have tried factoring the first 2 terms and i come up with x2(x+2) - 16 but I don't know where to go from there. Any help would be appreciated.

 

[Mark44]

Homework Statement

It's asking me to find all the real and complex zeros of the function x^3 + 2x^2 - 16.

Homework Equations

The Attempt at a Solution

I have tried factoring the first 2 terms and i come up with x2(x+2) - 16 but I don't know where to go from there. Any help would be appreciated.

This is not really a very good start. Instead you should see if you can find a number r such that x³ + 2x² - 16 = (x - r) * (x² + lower degree terms).

The Rational Root Theorem (you can search for this on the web) says that if r is a root of your cubic polynomial, it has to be a number that evenly divides -16. The only candidates are ±1, ±2, ±4, ±8, and ±16. Does your textbook mention this theorem? Does your textbook show any examples of similar problems? Do you read your textbook?