208

a)
$\frac{x^2}{2}+x+2-\left(\frac{x^2}{3}+\frac{3}{4}x+2\right)$
$\frac{x^2}{2}+x+2-\frac{x^2}{3}-\frac{3}{4}x-2$
$\frac{3x^2}{6}-\frac{2x^2}{6}+x-\frac{3}{4}x+2-2$
$\frac{1}{6}x^2+\frac{1}{4}x$
b)
$12\left(\frac{x^2}{2}-\frac{x}{3}\right)-3x^2+4x+1$
$\frac{12x^2}{2}-\frac{12x}{3}-3x^2+4x+1$
$6x^2-4x-3x^2+4x+1$
$3x^2+1$
c)
$-\left(x-2\right)\left(3x+1\right)$
$-\left(3x^2+x-6x-2\right)$
$-3x^2+5x+2$
d)
$0{,}5\left(2x+3\right)\left(x-0{,}5\right)$
$0{,}5\left(2x^2-x+3x-1{,}5\right)$
$x^2+x-0{,}75$