Jack rewrites the quadratic 9x^2 - 30x - 42 - x^2 - 2x in the form of (ax + b)^2 + c, where a, b, and c are all integers. What is ab?
+36916 9x^2 - 30x - 42 - x^2 - 2x =
8x^2 - 32x - 42 = 0
8 (x^2 - 4x) - 42 = 0 'Complete the square' for 'x'
8 ( x-2)2 - 32 -42 = 0
8 (x-2)2 - 74 = 0 <====== Now you can see a b and c to finish
