Question

I need calculus help.

Find the differential of the function y=x3sin(6x).
i found that to be 2sec^2(x) which is correct.
next i need to Evaluate dy and Δy when x=π/4 and dx=−0.2

what is dy: and Δy:

Answer 1

\[\large y=x^3 \sin(6x)\]Applying the product rule gives us,
\[\large dy=\left[3x^2\sin(6x)+6x^3\cos(6x)\right]dx\]

Hmm I don't quite understand how you got to 2sec^2(x).