Question

помогите решить уравнение! 3х2-10х+7=0 2) -4Х2-12Х+7=0

Answer 1

3х²-10х+7=0
а=3, в=-10, с=7
Д=в²-4ас=-10²-4*3*7=100-84=16
х1= $frac{-b- sqrt{D} }{2a} = frac{10- sqrt{16} }{2*3} = frac{6}{3} = 2$
x2= $frac{-b+ sqrt{D} }{2a} = frac{10+ sqrt{16} }{2*3} = frac{14}{6} = frac{7}{3} =2 frac{1}{3}$
____________________
-4x²-12х+7=0
а=-4, в=-12, с=7
Д=в²-4ас=-12²-4*(-4)*7=144+112=256
х1= $frac{-b- sqrt{D} }{2a} = frac{12- sqrt{256} }{2*(-4)} = frac{-4}{-8} = 0,5$
х2=  $frac{-b+ sqrt{D} }{2a} = frac{12+ sqrt{256} }{2*(-4)} = frac{28}{-8} = -3,5$