Question: Find the partial derivatives, $f_x(x, y)$ and $f_y(x,y)$, of the function $$f(x,y)=\int_y^xcos(3t^2+9t-1)dt$$
My attempt is as follows.
Plug in $u$:
and I don't know how to continue.
I've been stuck on this question for a few days now. Tried searching across all platforms but none has similar questions like this.
WolframAlpha shows an answer that involves the Fresnel C and S integrals but my class hasn't mentioned this anywhere.