$\frac{cosx-cos3x}{sinx-sin3x}=-tan2x$

$\int_0^l\left(\left(h+p\right)\cdot x^2+hl^2+pl^2-pl\cdot x+h\cdot x^2\right)dx$

$\frac{a^4}{4}-\frac{a^2}{30}-\frac{2}{15}$

$\left(-10mn^4-2mn-12+8m^2n\right)+\left(-5m^2n^4-mn-7+8m^2n\right)$

$\left(2b^3-7c^2\right)^2$

$\sqrt{3\left(x^2-4x+4\right)}$

$\left(m+2n\right)+\left(m+2n\right)+\left(m+2n\right)+\left(m+2n\right)+\left(m+2n\right)+\left(m+2n\right)+\left(m+2n\right)+\left(m+2n\right)$