[GP2]

Lead metal is added to 0.140 M Cr³⁺_(aq).

Pb_(s)+2Cr₃⁺_(aq) <---> Pb²⁺_(aq)+2Cr²⁺_(aq)

Kc=3.2*10^-10

1. What is [Pb²⁺] at equilibrium?
2. What is [Cr²⁺] at equilibrium?
3. What is [Cr³⁺] at equilibrium?

I started with Kc = [Pb₂][Cr²⁺]² / [Cr³⁺]²

The terms turn out to [4x]³ / [0.140-2x]²

Do I have to negate the 2x?

I think this turns into a cubic equation, which is why it's giving me some trouble.

EDIT: Solved it!