Thread: Solving a Quadratic Equation by Factoring Question

I have the problem (x+2)^3 = x^3+8
I use the cube formula (x+y)^(3) = x^(3) + 3x^(2)y + 3xy^(2) + y^(3) and get 6x^(2) + 12x = 0 and solve for x and get -2.

But the book says 0 is also an answer. Can someone please tell me why, and why sometimes 0 is not an answer?

Thanks.

Originally Posted by dwatkins741

I have the problem (x+2)^3 = x^3+8
I use the cube formula (x+y)^(3) = x^(3) + 3x^(2)y + 3xy^(2) + y^(3) and get 6x^(2) + 12x = 0 and solve for x and get -2.

But the book says 0 is also an answer. Can someone please tell me why, and why sometimes 0 is not an answer?

Thanks.

factor ...



set each factor equal to 0 ...

I forgot to factor before setting it equal to zero. Btw, how do you make your math text like that?