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Mathematics 17 Online
OpenStudy (anonymous):

f(x)= 2x^2 - 3

OpenStudy (anonymous):

Find the zeroes?

OpenStudy (anonymous):

inverse function of f(x)= 2x^2 - 3

OpenStudy (anonymous):

Okay, first input y for f(x). \(f(x) = 2x^2 - 3\) \(y = 2x^2 - 3\)

OpenStudy (skullpatrol):

apply the inverse operations in the opposite order

OpenStudy (anonymous):

Then switch x and y: \(x = 2y^2-3\)

OpenStudy (anonymous):

Then solve for \(y\).

OpenStudy (anonymous):

what is the answer? :)

OpenStudy (anonymous):

\(x = 2y^2 - 3\) \(\Large\frac{x}{2} \) \(= y^2 - 3\)

OpenStudy (anonymous):

I will not tell you the answer, you will find it out on your own.

OpenStudy (anonymous):

Am I right so far? @skullpatrol

OpenStudy (anonymous):

Thank You :) Very much

OpenStudy (skullpatrol):

nope, first add 3 to both sides

OpenStudy (anonymous):

Oh.

OpenStudy (anonymous):

How to find?

OpenStudy (anonymous):

\(x=2y^2−3\) \(x + 3 = 2y^2\)

OpenStudy (anonymous):

Do we divide by 2 or find the exponent next? @skullpatrol

OpenStudy (anonymous):

Or square the other side*

OpenStudy (skullpatrol):

divide by 2

OpenStudy (anonymous):

Okay, can you do that @jhayferrer

OpenStudy (skullpatrol):

$$\Huge \frac{x+3}{2}=y^2$$

OpenStudy (anonymous):

oh that's the answer men :)

OpenStudy (anonymous):

Argh.. Hold on. \[y = \sqrt{\frac{x+3}{2}}\]

OpenStudy (anonymous):

and then?

OpenStudy (anonymous):

That's your final answer, do you see how we did it?

OpenStudy (anonymous):

no :(

OpenStudy (skullpatrol):

you need the plus or minus sign

OpenStudy (anonymous):

Well you change it to: \(f^{-1}(x) = \sqrt{\Large\frac{x+3}{2}}\)

OpenStudy (anonymous):

Where? @skullpatrol

OpenStudy (skullpatrol):

in front of the square root

OpenStudy (anonymous):

Oh.

OpenStudy (anonymous):

i find thank you very much

OpenStudy (anonymous):

How about inverse function of f(x)=x

OpenStudy (anonymous):

Okay, well @jhayferrer First we changed \('f(x)'\) to \(y\). \(y= 2x^2 - 3\) Then we switched the \(x\) and \(y\) variables. \(x = 2y^2 - 3\) Now we're trying to get the \(y\) variable by itself. So we have to add the \(3\). \(x + 3 = 2y^2\) Then we divide the \(2\) because it's being multiplied by the \(y\). \(\Large\frac{x+3}{2}\)\( = y^2\) Now to get rid of the exponent \('2'\), we have to square the other side: \(y = \sqrt{\Large\frac{x+3}{2}}\)

OpenStudy (anonymous):

Then: \(f^{-1}(x) = \pm\sqrt{\Large\frac{x+3}{2}}\)

OpenStudy (anonymous):

\(f(x)=x\) Change the \(f(x)\)to \(y\), then switch the \(x\) and \(y\).

OpenStudy (anonymous):

Now what do we have? @jhayferrer

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