How do you find the inverse of #y=e^(3x+1)#?

1 Answer
Nov 26, 2015

If #z_x# is the inverse of #y_x =e^(3x+1)#
then #z_x = (ln(x)-1)/3#
(with some restrictions)

Explanation:

If #z_x# is the inverse of #y_x#
#color(white)("XXX")y_(z_x) = x# (by definition of inverse)

but
#color(white)("XXX")y_(z_x) = e^(3z_x+1)# (by definition of #y_x#)

therefore
#color(white)("XXX")e^(3z_x+1) = x#

and taking the natural log of both sides
#color(white)("XXX")3z_x+1=ln(x)#

#rArr#
#color(white)("XXX")z_x= (ln(x)-1)/3#

Note however that for certain values of #x#,
#y_x# generates non-reversible values (because of limitations on argument values for the #ln# function)