X(11-6x)-20+(2x-5)^2=0
11x-6x^2-20+4x^2-20x+25=0 4x^2-6x^2+11x-20x+25-20=0 -2x^2-9x+5=0 2x^2+9x-5=0 D=81-4*2*(-5)=81+40=121 D^1/2=11 X1=(-9+11)/4=0,5 X2=(-9-11)/4=-5