comosition of functions!Help!?

Question

Find (f o g)(x) and its domain, (g o f)(x) and its domain, (f o g)(-2) and (g o f)(-2) of the following problem:
1.f(x) = 2x + 3, g(x) = 3x -1
2.f(x) = x+ 2, g(x) = 2x2
3.f(x) = x2 – 1, g(x) = x + 1

Answer 1

1. f(x) = 2x + 3, g(x) = 3x -1
(f o g)(x) = 2(3x -1) + 3 = 6x + 1
(g o f)(x) = 3(2x + 3) -1 = 6x + 8
(f o g)(2) = 13
(g o f)(2) = 20
2. f(x) = x + 2, g(x) = 2x^2
(f o g)(x) = 2x^2 + 2
(f o g)(2) = 10
(g o f)(x) = 2(x + 2)^2
(g o f)(2) = 32
3. f(x) = x^2 - 1, g(x) = x + 1
(f o g)(x) = (x + 1)^2 - 1
(f o g)(2) = 8
(g o f)(x) = x^2 - 1 + 1 = x^2
(g o f)(2) = 4

The domain of all of the above is all x

Answer 2

1. fog (x) = 2g(x) + 3 = 2(3x-1) + 3 = 6x + 1 : for all real x
2. fog (x) = g(x) + 2 = 2x^2 + 2 : for all real x
3. fog (x) = (x+1)^2 -1 = x(x+2) : for all real x

1. fog(-2) = -12 + 1 = -11
2. fog(-2) = 2(4) + 2 = 10
3. fog(-2) = -2(-2+1) = 2

Use the similar method for gof (x).