$45\cdot99$

$\left(7mn^2+2w^3\right)\left(7mn^2-2w^3\right)$

$k^2-24k-25=0$

$restar\:\frac{7}{3}a+\frac{5}{4}bc-\frac{7}{9}xy^2-\frac{9}{3}a^2de\frac{1}{5}a+\frac{7}{9}bc-\frac{4}{8}yx^2-\frac{7}{5}a^3$

$5x-4>x+8$

$\int_0^{\frac{\pi}{2}}\left(\sec^2x+\sin4x\right)dx$

$-a+4a$