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What is the inverse of this logarithm equation?

  • #1

Homework Statement



What is the inverse of this logarithm equation?

y=-log5(-x)




i tried it and i got y=-5(-x)


hm.. you know how people say that if you want to find the inverse graph of something just switch the x and y coordinates from the table of values? Well i also tried that approach and apparently the inverse is y=log5x

atleast thats how it looks on table of values and on the graph....i dunno why i went with the y=-5(-x)


I dont know if i got it right or not, someone kind enough to take a look and see if i got it right or not? or maybe just give me the solution outright so i know if i did it correctly or not? :P
 
Last edited:

Answers and Replies

  • #2
symbolipoint
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Your result is correct. If you start from your original equation, multiply both sides by negative 1, you can easily switch x and y, and carry couple simple steps to find y as a function of x.
 
  • #3
hm... so y=log5x is correct?
 
  • #4
symbolipoint
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hm... so y=log5x is correct?
No! Your first result was correct. y=-5^(-x)
 
  • #5
ahh ok ty
 
  • #6
symbolipoint
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Original equation: [itex]y=-log_{5}(-x)[/itex]

[itex]-y=log_{5}(-x)[/itex]
Now express exponential form :
[itex]5^{-y}=-x[/itex]

Now, switch x and y to create inverse:
[itex]5^{-x}=-y[/itex],

and then simply, [itex]y=-5^{-x}[/itex]
 
  • #7
Mentallic
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Homework Statement



What is the inverse of this logarithm equation?

y=-log5(-x)




i tried it and i got y=-5(-x)


hm.. you know how people say that if you want to find the inverse graph of something just switch the x and y coordinates from the table of values? Well i also tried that approach and apparently the inverse is y=log5x

atleast thats how it looks on table of values and on the graph....i dunno why i went with the y=-5(-x)


I dont know if i got it right or not, someone kind enough to take a look and see if i got it right or not? or maybe just give me the solution outright so i know if i did it correctly or not? :P
To check if you're right, when you get to the equation [itex]x=-5^{-y}[/itex], just plug that value of x into your original equation [itex]y=-\log_5(-x)[/itex] and see if you get an equality.
 

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