Dushzhanov987

siestarjoki

1) 2x^2 +3x +4 =0; D=b^2 -4ac =9-32; D<0, корней нет

2) -x^2 +9 =0 <=> x^2 =9 <=> |x|=3 <=> x1=3; x2=-3

3) x^2 -5x =0 <=> x(x-5)=0 <=> x1=0; x2=5

4) x^2=0 <=> x=0