Question

1) 5x^2-36x+7=0
2) 7x^2+20x-3=0
3) 5x^2-26x+5=0
4) 8x^2+15x-2=0
5) x^2-x-6=0

Решите пожалуйста

Answer 1

1)$5 x^{2} -36x+7=0 \ k=36/2=18 \ D= 18^{2} - 5*7=324-35=289 \ x_{1} = frac{-18- sqrt{289} }{5} = -7 \ x_{2} = frac{-18+ sqrt{289} }{5} = -0.2$
2)$7x^{2} +20x-3=0 \ k=20/2=10 \ D= 10^{2} -7*(-3)=100+21=121 \ x_{1} = frac{-10- sqrt{121} }{7} = -3 \ x_{2} = frac{-10+ sqrt{121} }{7} = frac{1}{7}$
3)$5x^{2} -26x+5=0 \ k=26/2=13 \ D= 13^{2} -5*5=169-25=144 \ x_{1} = frac{-13- sqrt{144} }{5} = - 5 \ x_{2} = frac{-13+ sqrt{144} }{5} = - 0.2$
4)$8x^{2} =15x-2=0 \ D= 15^{2} - 4*8*(-2)=225-(-64)=289 \ x_{1} = frac{-15- sqrt{289} }{16} = -2 \ x_{2} = frac{-15+ sqrt{289} }{16} =0.125$
5)$x^{2} -x-6=0 \ D =1^{2} -4*1*(-6)=1-(-24)=25 \ x_{1} = frac{1+ sqrt{25} }{2} =3 \ x_{2} = frac{1- sqrt{25} }{2} = - 2$