Trig Section P-9

Inverse Functions

If f(g(x)) = x and g(f(x)) = x for all x's in the appropriate domains, then g(x) is the INVERSE of f(x)

g(x) = f -1(x)

f(f -1(x) = x and f -1(f(x) = x

domain f(x) = range f -1(x) and
range f(x) = domain f -1(x)

Finding an inverse algebraically

1) Replace f(x) by y
2) Swap all x's and y's
3) Solve for y
4) Replace y with f -1(x)

Test: is the range of f(x) = domain of
f -1(x) and vice versa?

Do all homework divisible by 3
Prepare for test on Thursday. See sample test page 117