Question

Can someone help? I’m really stuck!

The expression 24x^2-19x-35 can be written as (Ax-5)(2Bx+C), where A, B, and C are positive numbers. Find AB-3C.

Answer 1

24x² -19x-35= 0

24x² -(40-21)x -35= 0

24x²-40x+21x-35=0

8x(3x-5) +7(3x-5)=0

(3x-5) (8x+7)=0

(Ax-5)(2Bx+C) = (3x-5) (8x+7)

Comparing them,

A = 3

B = 4

C= 7

AB-3C = (3×4) - 3(7) = 12-21 = -9