$1.3-\left|-1.9\right|$

$sec^2\left(x+y\right)$

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

$\left(x^2-\:5x\right)^2+\:10\left(x^2-\:5x\right)\:+\:24$

$\frac{x+2}{x}<4$

$-4x+6y$

$\frac{8x^{2}y^{3}+8xy-6x^{2}y^{2}z-6xz}{2xy^{2}+2}$