Kenneth S. answered • 02/27/16
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Expert Help in Algebra/Trig/(Pre)calculus to Guarantee Success in 2018
you need to be clear when you send a function that has exponents; shall we assume that the entire exponent is (3sinxcosx)?
Explicit parentheses are always advisable in order to remove any doubt; did you mean y = y3 (sin x cos x) with only the 3 in the exponent position? [That's what the order-of-operations dictates when parentheses are omitted.]
I'll ASSUME the latter is the case, in which case y' = 3x2(sin x cos x) + x3[cos x cos x +sin x (-sin x)]
where the product rule has to be used twice. Simplification not shown.
Corrected (there were y letters on the right side of my y' result, formerly. Sorry!
Kenneth S.
So you have confirmed that my assumption was correct. Therefore I have given you the correct y' and you can simplify it.
Study what I wrote (used product rule twice) -- no chain rule application in this particular problem.
Do you fully understand chain rule, i.e. (uv)' = u'v + uv' ? That's the key!
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02/27/16
Pia R.
02/27/16