Question

If f(x) = x2 − 81 and g(x) = x+9/x-9, find g(x) · f(x).

Answer 1

f(x) = x² - 81 = ( x+ 9)(x - 9) Difference of two squares

g(x) = x+9/x-9

g(x) . f(x) = x + 9/ x - 9 × (x+9)(x - 9)

= ( x + 9)(x +9)

= ( x + 9)²

= x² + 18x + 81

Hope this helps.