1) 3х²+10х+7=0
D=b²-4ac=100-84=16
√16=4
x₁=-b+√D/2a = -10+4/6=-1
x₂=-b-√D/2a = -10-4/6= -7/3
2)-7x²-4x+11=0
D=16+308=324
√324=18
x₁,₂= 4±18/-14; x₁=-6/7; x₂=1
4x-2=0
Второй способ :
f(- 5) = 1
f(- 3,5) = 2,5
f(- 2) = 4
f(1,5) = 3,5
f(3) = 3