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
а)
D=16+9=25
x=(-4+-5)/3
x1=-3 x2=1/3.
б)
D=9-4=5
x1=-3+sqrt(5)
x2=-3-sqrt(5).
