I need to put y=(x+3)(x+4) into quadratic form and find the values of x.

I solved the quadratic equation as y= x ²+7x+12

And by using the quadratic formula I got the answer of x=-3 and -4 but when I substitute those values into the equation, I get different answers.

I thought you were meant to get two values for x but they would both equal the same number when put into the equation.

Am I doing something wrong here or can someone explain what's going on?