2010-12-22, 10:25 PM
The cone one seems annoying.
y = 9^(-x)
y = e^(-x ln 9) <-- exponent rule
y' = e^(-x ln 9) (- ln 9) <-- chain rule
y' = 9^(-x) (- ln 9) <-- put it back
y' = -9^(-x) ln 9.
y = 9^(-x)
y = e^(-x ln 9) <-- exponent rule
y' = e^(-x ln 9) (- ln 9) <-- chain rule
y' = 9^(-x) (- ln 9) <-- put it back
y' = -9^(-x) ln 9.

