Ответ:

[tex]y=tg(x^2+3)\\\\y’=\Big (tg(x^2+3)\Big )’=\frac{1}{cos^2(x^2+3)}\cdot (x^2+3)’=\frac{1}{cos^2(x^2+3)}\cdot 2x=\frac{2x}{cos^2(x^2+3)}[/tex]