Quick inverse question

  • Thread starter Nelo
  • Start date
  • #1
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Homework Statement



Inverse of g(x) = x/3 -5


Homework Equations





The Attempt at a Solution



The inverse of the function

g(x) = x/3 -5
x= y/3 -5
x +5 = y/ 3
3x + 15 = y

Is this correct?

Or is it x+5 /3 ?
 

Answers and Replies

  • #2
1,335
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Your original looks correct.

If you have a graphic calculator, graph them both, the inverse should be a 90* rotation from the original, since you essentially have the same function with swapped axis.
 
  • #3
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If you want to check to see if the inverse function you found is correct, all you need to do is form a composite function of the original function and its inverse. If the composite function of g(x) and g-1(x) is equal to x, then the inverse you found is correct.

[itex]g[g^{-1}(x)]=(\frac{3x+15}{3})-5=(x+5)-5=x[/itex]

Yes, the inverse you found is correct.
 

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