# Proving using ε/δ definition

## Homework Statement

Prove using ε/δ definition,

lim x tends to -1 (x^3+2x^2) = 1

## The Attempt at a Solution

I have done to the step where δ(δ^2-δ-1) ≤ δ ≤ ε

so i choose ε=min(2,ε)

Not sure whether I am correct or not

Related Calculus and Beyond Homework Help News on Phys.org
vela
Staff Emeritus
Homework Helper
I hope you realize that
$$\lim_{x \to -1} (x^3+2x^2) \ne 1$$ so you're going to have a tough time proving it. In any case, you need to show more of your work. We can't see your paper or read your mind to see what you actually did.

pasmith
Homework Helper
i hope you realize that
$$\lim_{x \to -1} (x^3+2x^2) \ne 1$$
$(-1)^3 + 2(-1)^2 = -1 + 2 = 1$. Last time I checked, $x^3 + 2x^2$ was continuous everywhere.

vela
Staff Emeritus
Homework Helper
Well, now I feel like an idiot. And I checked it over and over and kept getting -1.