+0  
 
0
41
2
avatar+62 

If f(x) = 5x 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
edited by SurpriseMe  Apr 13, 2018
Sort: 

2+0 Answers

 #1
avatar+12227 
+2

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
edited by ElectricPavlov  Apr 14, 2018
 #2
avatar+6943 
+2

f-1(k)  =  -3       so....

 

k  =  f(-3)

                        And   f(-3)  =  5-3

k  =  5-3

 

k  =  1 / 53

 

k   =   1 / 125

 

k   =   0.008

 
hectictar  Apr 14, 2018

15 Online Users

avatar
avatar
avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details