Y=cosx * sin3x х0=-П/2 производные

[latex]y=cosx\cdot sin3x\; ,\; \; x_0=-\frac{\pi}{2}\\\\y'=-sinx\cdot sin3x+cosx\cdot 3cos3x\\\\y'(-\frac{\pi}{2})=-\underbrace{sin(-\frac{\pi}{2})}_{-1}\cdot \underbrace{sin (-\frac{3\pi}{2})}_{1}+\underbrace {cos(-\frac{\pi}{2})}_{0}\cdot 3\cdot \underbrace{cos(-\frac{3\pi}{2})}_{0}=1[/latex]