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Mathematics 18 Online
OpenStudy (x3_drummerchick):

WILL GIVE MEDALS! can anyone help me figure out how they got the simplified answer? i feel like they jumped alot of steps or something. the picture is posted below

OpenStudy (codingking03):

where?

OpenStudy (x3_drummerchick):

OpenStudy (codingking03):

@blm1

OpenStudy (x3_drummerchick):

i knew how to take the derivative, but the simplifying is messing me up :(

OpenStudy (x3_drummerchick):

@phi

OpenStudy (x3_drummerchick):

@welshfella

OpenStudy (mathstudent55):

Do you understand the line following the line that says Apply the quotient rule?

OpenStudy (x3_drummerchick):

yes

OpenStudy (mathstudent55):

Do you also understand the derivative of x is 1, and the next derivative?

OpenStudy (x3_drummerchick):

yes, i was able to take the derivative in its entirety, i just don't understand how they went from -48 times (....) to the simplified 144 times (...)

OpenStudy (x3_drummerchick):

how did they simplify all that?

OpenStudy (mathstudent55):

Ok. Let's go through it step by step.

OpenStudy (x3_drummerchick):

please! thatd be awesome

OpenStudy (mathstudent55):

\(-48\dfrac{1(x^2 + 12)^2 - 4x(x^2 + 12)x}{((x^2 + 12)^2)^2} \)

OpenStudy (mathstudent55):

Distribute the -48 and raise the denominator to the 2nd power. \(=\dfrac{-48(x^2 + 12)^2 +192x(x^2 + 12)x}{(x^2 + 12)^4} \)

OpenStudy (x3_drummerchick):

okay

OpenStudy (mathstudent55):

Both terms in the numerator and the denominator have a common factor of \(x^2 + 12\), so divide all terms by \(x^2 + 12\). \(=\dfrac{-48(x^2 + 12) +192x^2}{(x^2 + 12)^3} \)

OpenStudy (x3_drummerchick):

ohhh okay

OpenStudy (mathstudent55):

Distribute the -48 in the numerator and combine like terms. \(=\dfrac{-48x^2 -576 +192x^2}{(x^2 + 12)^3} \) \(=\dfrac{144x^2 -576}{(x^2 + 12)^3} \) Factor out 144. \(=\dfrac{144(x^2 -4)}{(x^2 + 12)^3} \)

OpenStudy (mathstudent55):

Just a little algebra manipulation.

OpenStudy (x3_drummerchick):

oh wow thank you so much

OpenStudy (mathstudent55):

You're welcome.

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