If f(x) = 5^{x} for al real values of x and f ^{-1}(k) = -3, then k = ?

I can't figure out the answer for this.

SurpriseMe
Apr 13, 2018

#1**+3 **

Find the inverse.....solve for x

y=5^x

log y = x log 5

logy /log5 = x now change the x's and y's

y= logx/log5 = f^-1(x)

f^-1(k) = -3 = log k/log5 k= .008

ElectricPavlov
Apr 14, 2018