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Answer:
a) J(K(x)) = x; K(J(x)) = x; functions are inverses
b) f(g(x)) = 8 -x; g(f(x)) = -x; functions are not inverses
c) f(x) = 4 -x; f^-1(x) = 4 -x. g(x) = x -4; g^-1(x) = x +4
Step-by-step explanation:
a) Substitute for the function argument in the usual way. If the functions are inverses, their composite is the identity function.
J(K(x)) = J(1/3x -2) = 3(1/3x -2) +6 = x -6 +6 = x . . . . functions are inverses
K(J(x)) = K(3x +6) = 1/3(3x +6) -2 = x +2 -2 = x . . . . functions are inverses
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b) f(g(x)) = f(x -4) = 4 -(x -4) = 4 -x +4 = 8 -x . . . . functions are not inverses
g(f(x)) = g(4 -x) = (4 -x) -4 = -x . . . . functions are not inverses
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c) To find the inverse function for y = f(x), solve x = f(y).
The inverse of f(x) = 4 -x is ...
x = f(y) = 4 -y
y = 4 -x . . . . . add y-x to both sides
f^-1(x) = 4 -x
and for g(x) = x -4, the inverse is ...
x = g(y) = y -4
x +4 = y
g^-1(x) = x +4
