$\left(a^2+3a\right)\left(a^2-3a\right)$

$2\log\left(5\right)+\log\left(x+1\right)=1+\log\left(2x+7\right)$

$25x^2+30xy+9y^2$

$h\left(t\right)=-t^2+4t+5$

$\frac{\left(\tan\left(x\right)-\cot\left(x\right)\right)}{\tan\left(x\right)+\cot\left(x\right)}=2\sin^2x-1$

$xy^4=4$

$\left(-3+8\right)\cdot\left(-7\right)$