1) 10x^2+10=0.2 2) 2x^2+8=0 4) дискрименант равен нулю 10x^2=0.2-10 2x^2=-8 3) не знаю 10x^2=-9.8 x^2=-8/2 x^2=-9.8/10 x^2=-4 x^2=-0.98 x=-2 x=-0.46