Find (fg) (-4) when f (x) = x + 5 and g (x) = 5x2 + 10x - 5.

F g = (x + 5) · (5 x² + 10 x - 5) =

= 5 x³ + 10 x² - 5 x + 25 x² + 50 x - 25 = 5 x³ + 35 x² + 45 x - 25 =

= 5 (x³ + 7 x² + 9 x - 5)

(f g) ( - 4) = 5 * ( - 64 + 112 - 36 - 5) = 5 * 7 = 35