Помогите пожалуйста, 26 вариант

Решите задачу:

$1)\; \; \int \frac{dx}{cos^2(15x+9)}=[\, t=15x+9\; ,\; dt=15dx\; \to \; \; dx=\frac{dt}{15}\, ]=\\\\=\frac{1}{15}\int \frac{dt}{cos^2t}=\frac{1}{15}\cdot tgt+C=\frac{1}{15}\cdot tg(15x+9)+C\\\\2)\; \; \int e^{x}\cdot 6^{2-e^{x}}dx=[\, t=2-e^{x}\; ,\; dt=-e^{x}dx\, ]=\\\\=-\int 6^{t}\cdot dt=-\frac{6^{t}}{ln6}+C=-\frac{6^{2-e^{x}}}{ln6}+C$

$3)\; \; \int \frac{x\, dx}{25-64x^4}=\int \frac{x\, dx}{5^2-(8x^2)^2} =[\, t=8x^2\; ,\; dt=16x\, dx]=\\\\=\frac{1}{16}\int \frac{dt}{5^2-t^2} =\frac{1}{16}\cdot \frac{1}{10}ln\left |\frac{5+t}{5-t}\right |+C=\\\\=\frac{1}{160}\cdot ln\left |\frac{5+8x^2}{5-8x^2}\right |+C$