$\sin\left(\frac{\pi}{4}+x\right)-\sin\left(\frac{\pi}{4}-x\right)$

$\left(7a-3bc\right)^{2}$

$70-2x>30+8x$

$\left(-5a^2m^3\right)^3$

$\left(5x^2-1\right)^3\cdot20x$

$\log\left(x^2+2x-15\right)=4\log\left(2\right)$

$\lim_{x\to\infty}\left(\frac{x^2+1}{x^2-2}\right)^{x^2}$