Помогите пж с квадратным уравнением !!! 1) 5x^2-2x-7=0 2) 11x^2=10x-1=0 3) 10x^2-9x-1=0...

1)Д=b²-4ac=4-4*5*(-7)=4+140=144
x₁= $\frac{2- \sqrt{144} }{2*5} = \frac{2-12}{10} = \frac{-10}{10} =-1$
x₂= $\frac{2+ \sqrt{144} }{2*5} = \frac{2+12}{10} = \frac{14}{10} =1.4$
2)D=100-4*11*(-1)=100+44=144
x₁= $\frac{10-12}{2*11} = \frac{-2}{22} = \frac{-1}{11}$
x₂= $\frac{10+12}{2*11} = \frac{22}{22} =1$
3)D=81-4*10*(-1)=81+40=121
x₁= $\frac{9-11}{2*10} = \frac{-2}{20} =-0.1$
x₂= $\frac{9+11}{2*10}= \frac{20}{20} =1$
4)D=1936-4*30*(-10)=1936+1200=3136
x₁= $\frac{44-56}{2*30} = \frac{-12}{60} =-0.2$
x₂= $\frac{44+56}{2*30} = \frac{100}{60} =1 \frac{2}{3}$