# derivatives (division and chain rule)

• Sep 29th 2009, 10:57 PM
dogmom09
derivatives (division and chain rule)
y=(4x^2+1)^8/12x^3-1

I know that to start I must set y= u^8 and u= 4x^2+1

I must then use the quotient rule somehow...

Thanks so much for any and all help!
• Sep 29th 2009, 11:13 PM
DeMath
Quote:

Originally Posted by dogmom09
y=(4x^2+1)^8/12x^3-1

I know that to start I must set y= u^8 and u= 4x^2+1

I must then use the quotient rule somehow...

Thanks so much for any and all help!

Hint:

$y= \frac{{{{\left( {4{x^2} + 1} \right)}^8}}}{{12{x^3} - 1}}.$

$\frac{{dy}}
{{dx}} = \frac{{\left( {12{x^3} - 1} \right) \cdot \frac{d}
{{dx}}{{\left( {4{x^2} + 1} \right)}^8} - {{\left( {4{x^2} + 1} \right)}^8} \cdot \frac{d}
{{dx}}\left( {12{x^3} - 1} \right)}}
{{{{\left( {12{x^3} - 1} \right)}^2}}} = \ldots$