Ответ:

x²+7x+6=0; x1= -1

x1+x2= -7 x2= -6

x1×x2=6

5x²-7x+2=0

D=49-40=9

x1=(7+3)÷10=1

x2=(7-3)÷10=0.4

x²=7x+18

x²-7x-18=0

x1+x2=7 x1= -2

x1×x2= -18 x2=9

x²+3x-54=0

x1+x2= -3 x1= -9

x1×x2= -54 x2=6

2x²-7x+3=0

D=49-24=25

x1=(7+5)÷4=3

x2=(7-5)÷4=0.5