The equation is .

Apply difference of squares formula: .

Apply zero product property: If then .

First term is .

Apply subtraction property of equality: If a = b then a c = b  c.

Subtract 6 from each side. 

Apply additive inverse property: .

Multiply each side by 3.

Check:

To check the first solution substitute  in .

Then the first solution is "true".

Second term is .

Apply addition property of equality: If a = b then a + c = b + c.

Add to each side.

Apply additive inverse property: .

Multiply each side by 3.

Check:

To check the first solution substitute  in .

Then the first solution is "true".

The solution are and .