FUNCTIONS 7

If F(x) = 4x² + 12x - 420; find F(6) - F(2).

solution

PROCEDURE:

i) Find F(6)

ii) Find F(2)

iii) Do F(6) - F(2).

i) Find F(6)

F(x) = 4x² + 12x - 420

F(6) = 4(6)² + 12(6) - 420

F(6) = 4(6x 6) + (12 x 6) - 420

F(6) = 144 + 72 - 420

F(6) = 216 - 420

F(6) = -204.

ii) Find F(2)

F(x) = 4x² + 12x - 420

F(2) = 4(2)² + 12(2) - 420

F(2) = 4(2 x 2) + (12 x 2) - 420

F(2) = 32 + 24 - 420

F(2) = 56 - 420

F(2) = -364

iii) Do F(6) - F(2).

      F(6) - F(2) = -204 - (-364) = -204 + 364 = 160.

Hence F(6) - F(2) = 160.

TRY THIS..................

If F(x) = 11x² + 2x - 10; find F(7) - F(4).