# Homework Help: Roots of x^3 + 216

1. Sep 18, 2004

### Alkatran

I need to factorise x^3 + 216 to include (x+6):

(x + 6) \ (x^3 + 216) (lim where x approaches -6)

I broke it down to (x + 6i)(x^2 - 36i) ... but that's no good.

2. Sep 18, 2004

### arildno

Well, shouldn't polynomial division work fine?

3. Sep 18, 2004

### Pyrrhus

Remember

$$X^3 + Y^3 = (X+Y)(X^2-XY+Y^2)$$

4. Sep 18, 2004

### Pyrrhus

He has

$$\frac{x+6}{x^3 + 216}$$

$$\frac{x+6}{x^3 + 6^3}$$

5. Sep 18, 2004

### Alkatran

I got it fine before I even came back. I was trying to remember how to do long division and the cube rule that you guys posted. The start of the year, still getting restarted...