$2\cdot1\cdot7$

$\frac{\sec\left(x\right)}{\cos\left(x\right)}=\frac{1}{\cos^2\left(x\right)}$

$f\left(x\right)=x^7-2x^6+3x$

$5-\infty$

$\left(\frac{1}{2}-\frac{1}{2}\cos\left(2x\right)\right)^2$

$\left(4r^2+4r+1=0\right)$

$\left(12m^3-7n^4\right)\left(12m^3+7n^4\right)$