1
151 WebCalc Fall 2002-copyright Joe Kahlig
Quiz #15
MATH 151 Section
Name:
October 24, 2002
Show all your work.
1. Find the inverse of the function y =
√
5 − x.
swap variables.
√
x= 5−y
x2 = 5 − y
y = 5 − x2
Answer: y = 5 − x2 and with x ≥ 0
2. For the function f (x) = x5 − 3x3 + 6x with its inverse function g(x), compute g0 (4)
Since g0 (a) =
1
f 0 (g(a)) ,
we need to know what g(4) is.
g(4) = 2 is the same as saying f (2) = 4. looking at the equation we see that 2 = 1
so g0 (4) =
1
f 0 (g(4))
=
1
f 0 (1)
=
1
5−9+6
=
1
2