Answer: given and explained briefly below.
In these questions, we go right to left of the function to solve.
(a)
given that
f(x) = x - 3
g(x) = x + 3
(i) fg(x)
= f(x + 3)
= ( x +3 ) -3
= x
(ii) gf(x)
= g(x-3)
= (x-3)+3
= x
to find inverse, we have to make x the subject,
1)
f(x) = x - 3
f(x) + 3 =x
f^-1(x) = x + 3
2)
g(x) = x + 3
g(x) -3 = x
g^-1(x) = x -3
- f and g are inverses of each other
(b)
given that
f(x) = -1/4x
g(x) = 1/4x
fg(x) =
f(1/4x)
1/4(-1/4x)
= x
2)
gf(x)
g(-1/4x)
-1/4(1/4x)
= -x
to find inverse, we have to make x the subject,
1)
f(x) = -1/4x
-1/f(x) = 4x
f^-1(x) = -1/4x
2)
g(x) = 1/4x
x = 1/4g(x)
g^-1(x) = 1/4x
- f and g are not inverses of each other here.