$x^2-9x+20=0$

$x^2+11x=-18$

$3x^2-3x-6=0$

$x^2-153=8x$

$45+30x=-5x^2$

$\frac{1}{4}x^2+\frac{1}{4}x-\frac{1}{2}=0$

$8x^2+4x=4$

$2x^2+8{,}8x+8{,}4=0$

$13x^2+18{,}2x+3{,}12=0$