(1/4+0.31)*3=1.68
1) 1/4+0.31=25/100+0.31=0.25+0.31=0.56
2) 0.56*3=1.68
(1/4+0.31)*3=1,68
1) 1/4+0.31=1/4+31/100=25/100+31/100=56/100
2)56/100*3=56/100*3/1=168/100=1 68/100=1,68
D=b^2-4ac
D= 16-4*7*(-3)
D=16-(-84)=100
x1,2= -b+/-корень из 100
х1= -4+10/2*7=6/14
х1=3/7
х2=-4-10/14=-1
Ответ: 3/7; -1