$\lim_{n\to\infty}\left(\left(-3\right)^n\right)$

$\left(6y^2-5x^3b\right)^2$

$6^7\cdot6^5$

$1-\sec\left(x\right).\cos\left(x\right).\tan\left(x\right)=\cos^2\left(x\right)$

$5\left(92-978\right)$

$16x^2-16x+49$

$\lim_{x\to\infty}\left(\left(\frac{2x-3}{2x+5}\right)^{2x+1}\right)$