If 4 and 6 are solutions to ax2+bx+c=0, find the sum of the solutions for ax2-bx-c=0.
Solutions 4 and 6 means that :
(x-6)(x-4)=0
x^2 -10x + 24 =0 a = 1 b = -10 c = 24
Sub into second equation
x^2 + 10x -24 = 0
(x+12)(x-2) = 0 solutions are x = -12 and + 2 sum = -10