Diketahui f(x) = x²+2x, g(x) =x-5 Tentukan: a. fog (x) b. gof (x) c. gof (4)

a.(x-5)²+2(x-5)
  =x²-25+2x-10
  =x²+2x-35
b.x²+2x-5
c.gof(4)=x²+2x-5
            =4²+2.4-5
            =16+8-5
            =16+3
            =19