inverse functions! forgot my pre-calc!.:Resolved:.

Hello everyone, I forgot how to do inverse functions, can someone show me an example?
heres a problem:

Code:

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f(x) = 2x-3

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it says find the f^-1 which is just find the inverse and then describe the relationship between teh graphs.
Thanks for listening!:D

Quote:

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Originally posted by voidflux
Hello everyone, I forgot how to do inverse functions, can someone show me an example?
heres a problem:

Code:

---

f(x) = 2x-3

---

it says find the f^-1 which is just find the inverse and then describe the relationship between teh graphs.
Thanks for listening!:D

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Just solve for y:

f(y) = (3 + x)/2

Then again, college was 100 years ago ... so maybe someone else can verify whether or not I remember that correctly ... :=)

Thanks! that is the right answer but what do u mean solve for y?
I don't see how you got to your final answer, can you please write some steps for me or explain to me what ur logic was?
Thanks again! Sorry i'm slow heh:o

Muddy is correct. Don't think of it as a function for a while. So instead of

Code:

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f(x) = 2x-3

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, you've got

Code:

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y = 2x-3

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.

You then switch all isntances of the x and y, and then solve for y.

Code:

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x = 2y-3
x+3 = 2y
y = (x+3)/2

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So your answer is

Code:

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f(x) = (x+3)/2

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:)

Thanks guys! that helped alot!:D

That is the fastest way to solve the problem, and frequently used. If you want to ponder Inverse Functions, here is another way of looking at it.

For F's inverse, look at what F did to x.
X-------multiplies by 2----->2x-----subtracts 3-----> 2x-3

So, F's inverse does the opposite, in the opposite order!
x-------adds 3------->x+3---------divides by 2-------> (x+3)/2

This is just the long conceptual way of thinking about it,, anyway that's the joy of math, several ways of thinking about the same thing.

Quote:

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Originally posted by Jared
That is the fastest way to solve the problem, and frequently used. If you want to ponder Inverse Functions, here is another way of looking at it.

For F's inverse, look at what F did to x.
X-------multiplies by 2----->2x-----subtracts 3-----> 2x-3

So, F's inverse does the opposite, in the opposite order!
x-------adds 3------->x+3---------divides by 2-------> (x+3)/2

This is just the long conceptual way of thinking about it,, anyway that's the joy of math, several ways of thinking about the same thing.

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That's actually exactly what you're doing when you switch the x and the y, but most people don't think about it.

Ah, yes, but "thinking about it" is what makes it fun!