Mat question about find formulas.

a. f o g = (1/x)^2 +5 = 1/(x^2) + 5

b. g o f = 1/(x^2+5)

a. f。g = f (g(x)) (that is, putting g(x) = x into function f)
then we get the formula
f(g(x))= (1/x)^2 +5

b. g。f = g(f(x)) (that is, putting f(x) = x into function g)
then we get the formula
g(f(x)) = 1/f(x) = 1/(x^2 + 5)


you can think a function f as a computer program,
when you put something into this program,say value x',
the program(f(x)) will give you other things (the value of f(x'))
f。g means that what you put into the program is not x' , but g(x)