Hey someone.

The notation (fg)(x) is such that you work out u = g(x) first and then f(u) after-wards.

Doing the calculation gives us:

g(4) = 4^2 - 4 - 1 = 11

f(11) = SQRT(1 - 3*11)/11^3 = -SQRT(32)/11^3

Note the definition of composition I'm using can be found here:

Function composition - Wikipedia, the free encyclopedia.

Doing it the other way gives us:

f(4) = SQRT(-11)/64

g(f(4)) = -11/64^2 + SQRT(-11)/64 - 1

You may want to bring this up with your tutor.