- #1

silvermane

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## Homework Statement

We have x greater or equal to -1, and

(1+x)^3 greater/equal to 1 +3x.

We need to prove that 3x^2 +x^3 is greater or equal to zero for x greater/equal to -1.

## The Attempt at a Solution

I've simplified the inequality to 3x^2 greater/equal to 0, but now I need to show that this simplified inequality is true for x greater/equal to -1. I'm almost there, but need some guidance. Thanks for all your help in advance!