х²-8х+7=0
D=(-8)²-4×1×7=64-28=36,D>0, 2 корня
х1=8-√36/2×1=8-6/2=2/2=1
х2=8+√36/2×1=8+6/2=14/2=7
ответ:х1=1,х2=7
x2-8x+7=0
D= b2-4ac= 64-4*1*7= 36
√D= √36= 6
x1 = -b+√d/2a = 8+6/2*1 = 14/2=7
x2 = -b - √d/2a = 8-6/2*1 = 2/2 =1
