Ответ:

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