а)3х+8х-3=0 б)х2+6х+4=0 решите через дискременат

                                          Решение:

 а)

D=16+9=25x=(-4+-5)/3x1=-3  x2=1/3.

б)

D=9-4=5x1=-3+sqrt(5)x2=-3-sqrt(5).

а)3х^2+8х-3=0

D = b^2 - 4ac = 8^2 - 4*3*(-3) = 64 - (-36) = 64 + 36 = 100

VD = V100 = 10

                -b (+)(-) VD

X1/2 = -------------------

                        2a

x1 = (-8+10)/2*3 = 2/6 = 1/3

x2 = (-8-10)/2*3 = -18/6 = -3

б)х^2+6х+4=0

D = b^2 - 4ac = 6^2 - 4*1*4 = 36 - 16 = 20

VD = V20 = V(4*5) = 2V5

                -b (+)(-) VD

X1/2 = ------------------------

                        2a

               -6 + 2V5

x1 = ----------------------

                     2

                -6 - 2V5

x2 = -----------------------

                    2