$f\left(4\right)=\frac{2\left(4\right)+1}{-3\left(3\right)+3}$

$12^4\cdot12^4$

$\left(x^2-2\right)\left(x^2+2\right)-\:\left(x^2+1\right)^2$

$\left(f\cdot g\right)\left(x\right)\:\:f\left(x\right)=5-x\:\:\:g\left(x\right)=x^2-25$

$y+4x+5+5x-15$

$x^3+x^2-14x+6.x-3$

$\left(\frac{1}{2}a-2b\right)^3$