For what real values of $c$ is $x^2 - 8x - 4x + c + x^2 - 20x + x^2$ the square of a binomial?
Simplify as
3x^2 - 32x + c
We will have a square of a binomial when the discriminant = 0
32^2 - 4(3)c = 0
1024 = 12c
c = 1024/ 12 = 256/3
+1533 
