4times a number is 12 less than the square of that number. find the negative solution.

4 times a number : 4x
12 less than the square of that number : x^2 -12  (be careful here)
because it says that the first part is the other part you can set them equal each other : 
4x= x^2 -12 now solve it its a quadratic so it might have two solutions it looks like they only want a negative one
x^2 -4x -12   move everything over to the same side and factor it.  look for two factors that multiply to give you -12 and add to give you -4 
(x -6)(x +2) set each part equal to 0 and solve for x
you should get x= 6 and -2 since they asked for the negative solution it's -2