$9\sin\left(2x\right)=-\cos\left(x\right)$

$16w^{2\:}-56wx+49^2$

$\lim_{x\to\infty}\left(\frac{\left(x+\sqrt{\left(4x^2+8x+8\right)}\right)}{x}\right)$

$x+\sqrt{5x+19}=-1$

$2y\cdot5\sqrt{5y^2}-\frac{3}{2}y^4\cdot20\sqrt{5y^{10}}+\frac{1}{5}\cdot8\sqrt{5y^2}$

$2cot\left(2x\right)=cot\left(x\right)-tan\left(x\right)$

$\:-6.\left(x\right)=-\:18$