Find the largest value of $x$ such that $3x^2 + 17x + 15 = 2x^2 + 21x + 12 - 5x^2 + 17x + 34.$
Simplify as
6x^2 - 21x -31 = 0
x = [ 21 + sqrt [ 21^2 + 4(6)(31) ] ] / 12 = [21 + sqrt (1185) ] / 12
+750 
