Question

If (4x−7)2=ax2+bx+c for all values of x, what is the value of c(b+a)?

Answer 1

-1960

Explanation:

The expression on the left expands to ...

(4x -7)² = (4x)² +2(4x)(-7) +(-7)² = 16x² -56x +49

Matching coefficients, you have ...

• a = 16
• b = -56
• c = 49

Then the expression c(b+a) evaluates to ...

49(-56+16) = 49(-40) = -1960