Find g[f(4)] if f(x) = 5x and g(x) = 3x - 7.

Solution:

Given functions are

f(x) = 5x and g(x) = 3x - 7

g(f(x)) is a composite function.

To find g(f(x)) we have to replace x by f(x)

f(x) = 5x

g(f(x)) = 3(5x) - 7

= 15x - 7

To find g(f(4)) we replace x by 4 and we get

g(f(4)) = 15(4) - 7

= 60 - 7

= 53

Find g[f(4)] if f(x) = 5x and g(x) = 3x - 7.

Summary:

If f(x) = 5x and g(x) = 3x - 7 then the value of g[f(4)] = 53.