-2 и 1.............это точно
A)Xb=-b/2a Xb=-8/8=-1 Yb=4*(-1)^2-8-1=4-9=-5
b)x=6/(-6)=-1 y=-3+6+2=5
в)-1/-2=1/2 y=-1/4+1/2-1=-3/4
г)-10x^4+5x^2=y t=x^2 -10t^2+5t=y tв=-5/-20=1/4 Xв=+-1/2 y1=-10*(-1/2)^4+5*1/4=-10/16+5/4=-5/8+5/4 -5/8+10/8=5/8 y2=5/8
7x^2 - 9x +2 = 0
D= 81 - 4 * 7 * 2 =81-56 = 25
x1 = ( 9- 5) / 14 = 4/14 = 2/7
x2 = ( 9+5) / 14 = 1