Given f(x)=x+2f(x)=x+2 and g(x)=x-2g(x)=x2 how do you find f(g(x))?

1 Answer
May 3, 2016

f(g(x)) = xf(g(x))=x

Explanation:

f(g(x))f(g(x)) is denoting the composition of ff and gg. Just as how if we were applying ff to a number, we would substitute that number for each xx in f(x)f(x), as we are applying to ff to g(x)g(x), we substitute g(x)g(x) for each xx in f(x)f(x).

f(g(x)) = g(x)+2 = (x-2)+2 = xf(g(x))=g(x)+2=(x2)+2=x

As a side note, because f(g(x)) = g(f(x)) = xf(g(x))=g(f(x))=x, we say that ff and gg are inverses of one another.