Пожалуйста помогите решить!!!пожалуйста!!! 1.х^2-9х+14=0 2.х^2-11х+30=0 3.4х^2-20х+21=0 4.9х^2-12х-5=0

[latex] x^{2} -9x+14=0[/latex] [latex]D=b^{2} - 4ac=(-9)^{2} - 4*1*14=81-56=25[/latex] [latex] \sqrt{D} = \sqrt{25} =5 [/latex] [latex] x_{1}= \frac{9+5}{2} = \frac{14}{2} =7[/latex] [latex] x_{2} = \frac{9-5}{2} = \frac{4}{2} =2[/latex] Ответ:7;2. [latex] x^{2} -11x+30=0[/latex] [latex]D=b^{2} - 4ac=(-11)^{2} - 4*1*30=121-120=1[/latex] [latex] \sqrt{D} = \sqrt{1} =1[/latex] [latex] x_{1} = \frac{11+1}{2} = \frac{12}{2} = 6[/latex] [latex] x_{2} = \frac{11-1}{2} =\frac{10}{2}=5[/latex] Ответ:6;5 [latex]4 x^{2} -20x+21=0[/latex] [latex]D=b^{2} -4ac=(-20)^{2} - 4*4*21=400-336=64[/latex] [latex] \sqrt{D} = \sqrt{64} =8[/latex] [latex] x_{1} = \frac{20+8}{8} = \frac{28}{8} =3,5[/latex] [latex] x_{2} = \frac{20-8}{8} = \frac{20}{8} =2,5[/latex] Ответ:3,5;2,5 [latex]9 x^{2} -12x-5=0[/latex] [latex]D=b^{2} -4ac=(-12)^{2} - 4*9*(-5)=144+180=324[/latex] [latex] \sqrt{D}= \sqrt{324} =18[/latex] [latex] x_{1}= \frac{12+18}{18} = \frac{30}{18} [/latex] [latex] x_{2} = \frac{12-18}{18} = \frac{-6}{18} =[latex] \frac{-1}{3} [/latex] Ответ:[latex] \frac{30}{18} ; \frac{-1}{3} [/latex]