Composition of functions
Sets, relations and functions · Mathematics
Study notes
Q: f(x) = x + 2, g(x) = 3x. Find (a) (g∘f)(x) (b) (f∘g)(x) (c) (g∘f)(5). (a) (g∘f)(x) = g(x+2) = 3(x+2) = 3x + 6. (b) (f∘g)(x) = f(3x) = 3x + 2. Different! Order matters. (c) (g∘f)(5) = 3(5) + 6 = 21. (Check: f(5) = 7, g(7) = 21.)