22 次の関数 f(x), g(x) について, 合成関数 (gof) (x), (fog)(x) を求めよ。
(1) f(x)=3x+2, g(x)=x² +1
(gof)(x) = `9 (f(x)) = g(x+1)= (3x+2)+1 = 9x+12x+4+1 = 9x+12x+5
(fog)(x) = f(g(x)) = f(3x+2) = 3(x+1) + ≤ = 3ײ +5
(2)* f(x)=x², g(x)=√√x+1
(gof)(x) = g(√x+1)=√x+1
4
✓(fog)(x) = f(x) = x+1, (x²-1)
g(x)=√x+1の定義域はX2-1であるから