Question

1)int sin^3 5xdx

2)int 5sqrtx -2x^3 +4/x^2 .dx

3)int 2x+3/sqrt 2x^2-x+6

Answer 1

$1)\; \; \int sin^35x\, dx=\int sin^25x\cdot sin5x\, dx=\int (1-cos^25x)\cdot sin5x\, dx=\\\\=\int sin5x\, dx-\int cos^25x\cdot \underbrace {sin5x\, dx}_{-1/5\cdot d(cos5x)}=-\frac{1}{5}cos5x+ \frac{1}{5}\cdot \frac{cos^35x}{3}+C\; ;\\\\\\2)\; \; \int \frac{5\sqrt{x}-2x^3+4}{x^2}\, dx=\int (5x^{-3/2}-2x+4x^{-2})dx=\\\\=\frac{5x^{-1/2}}{-1/2}-\frac{2x^2}{2}+\frac{4x^{-1}}{-1}+C=-\frac{10}{\sqrt{x}}-x^2-\frac{4}{x}+C\; ;$