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Mathematics 17 Online
OpenStudy (quickstudent):

Can someone please help me with this? dividing rational expressions

OpenStudy (anonymous):

sure...

OpenStudy (quickstudent):

OpenStudy (quickstudent):

Can you please walk me through this?

TheSmartOne (thesmartone):

We need to work on one thing at a time :)

TheSmartOne (thesmartone):

So, let's only focus on the numerator part of the big fraction (:

OpenStudy (quickstudent):

OK:)

TheSmartOne (thesmartone):

\(\sf\Large \frac{x^2-3x-88}{x^2-49} =?\) The denominator of this looks easy to factor, considering the rule: \(\sf \Large a^2 - b^2 = (a+b)(a-b)\)

TheSmartOne (thesmartone):

Hint for factoring the numerator: 8 + (-11) = -3 8 x (-11) = -88

OpenStudy (quickstudent):

Ok, here is what I got factored: \[\frac{ (x-11)(x+8) }{ (x-7)(x+7) }\]

TheSmartOne (thesmartone):

Good job! :)

OpenStudy (quickstudent):

:)

TheSmartOne (thesmartone):

Now, let's factor the denominator. \(\bf\Huge \frac{x-11}{x^2-2x-63}\) Hint: the numerator is already factored the denominator's hints are: 7 + (-9) = -2 7 x (-9) = -63

OpenStudy (quickstudent):

Now I got: \[\frac{ x-11 }{ (x-9)(x+7) }\]

TheSmartOne (thesmartone):

Correct, so now we have: \(\bf\Large\frac{ (x-11)(x+8) }{ (x-7)(x+7)}\div \frac{ x-11 }{ (x-9)(x+7) }\)

TheSmartOne (thesmartone):

And we can simplify that too: \(\bf\Large\frac{ (x-11)(x+8) }{ (x-7)(x+7)}\times \frac{ (x-9)(x+7) }{ x-11 }\)

TheSmartOne (thesmartone):

Simplify it more: \(\bf\Large\frac{\cancel{ (x-11)}(x+8) }{ (x-7)\cancel{(x+7)}}\times \frac{ (x-9)\cancel{(x+7)} }{ \cancel{(x-11)} }\)

OpenStudy (quickstudent):

Oh, so that would make: \[\frac{ (x+8)(x-9) }{ (x-7) }\]

TheSmartOne (thesmartone):

And that's your answer :D

OpenStudy (quickstudent):

:D Thanks!

TheSmartOne (thesmartone):

Anytime! :D

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