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EXAMPLE 2Evaluating a Composite Function

The "inside" function g, in f(g(x)), is evaluated first.

Suppose that f(x)=1x+2 and g(x)=4x1.

  1. (a) (fg)(0)=f(g(0))=f(4)=14+2=12g(x)=4x1;g(0)=4
  2. (b) (gf)(1)=g(f(1))=g(13)=4131=423=6f(x)=1x+2;f(1)=13
  3. (c) (ff)(1)=f(f(1))=f(13)=113+2=173=37
  4. (d) (gg)(3)=g(g(3))=g(1)=411=2g(x)=4x1;g(3)=431=1