- f(x)=2x2-1. g(x)=√(x-2).
f(g(x)) is read "f of g of x", and it means to put the g(x) function in for x into the f(x) function. So:
f(√(x-2))=2(√(x-2))2-1.
Since squaring and taking a square root are inverse operations, they cancel out, and f(√(x-2))=2(x-2)-1.
2(x-2)-1=2x-4-1=2x-5.
You're given the domain x≥2, which is also the domain of the final function. Technically, if it weren't a composite function with the radical as part of the composition, the domain would be all real numbers. However, we cannot have a negative number under a square root sign, so x has to be at least 2. The final domain, given the original composition, should also be x≥2.
I'm not doing your whole assignment here, but if you need help understanding it, get in touch! Also, maybe this one will help you progress on the others.
I hope this helps, and take care!
Liz Z.