A=1;b=-8;c=3a+1
x1*x2=3a+1
x1+x2=8
а)3x^2=3a+1
4x=8
x1=2;x2=6
3*4=3a+1
12-1=3a
a=11/3
б)5x^2=3a+1
6x=8
x1=4/3, x2=20/3
5*16/9=3a+1
71/9=3a
a=71/27
в)7/9x^2=3a+1
16/9x=8
x1=4,5,x2=3,5
7/9*4,5^2=3a+1
3a=14,75
a=14,75/3
г)-3/7x^2=3a+1
4/7x=8
x1=14;x=-6
3a=-3/7(14)^2-1
a=-85/3