document.write( "Question 231658: every time i try this problem: $\"dy%2Fdx\"$ $\"+4%2Fcos%28x%29\"$ my answer is undefined \n" ); document.write( "

Algebra.Com's Answer #171403 by jsmallt9(3758) $\"\"$ $\"About$

You can put this solution on YOUR website!
I'm assuming the problem is:
\n" ); document.write( "Given: $\"y+=+4%2Fcos%28x%29\"$
\n" ); document.write( "Find: dy/dx
\n" ); document.write( "If this is not correct then then you'll have to repost your question, being clearer about the problem.

\n" ); document.write( "If the equation was
\n" ); document.write( " $\"y+=+4%2Fx+=+4x%5E%28-1%29\"$
\n" ); document.write( "would you know how to find its derivative? (I hope so because the solution to your problem depends on this.) This is a derivative where you bring the exponent down in front (as a coefficient) and then subtract one from the exponent:
\n" ); document.write( " $\"dy%2Fdx+=+%28-1%294x%5E%28%28-1-1%29%29+=+-4x%5E%28-2%29\"$

\n" ); document.write( "Of course we don't actually have $\"y+=+4%2Fx\"$ , we have $\"y+=+4%2Fcos%28x%29\"$ . In a situation like this, where you have a function where it would be nice to just have x, we use the Chain Rule. We find the derivative, treating cos(x) just as if it was x and then we multiply this result by the derivative of cos(x) (which is -sin(x):
\n" ); document.write( " $\"y+=+4%28cos%28x%29%29%5E%28-1%29\"$
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