Question

x-5x+6=0


x-8x+7=0



x-9x+8=0

Answer 1

1) - 4х = - 6
х = 6/4 = 3/2 = 1 1/2
2) - 7х = - 7
х = 1
3) - 8х = - 8
х = 1

Answer 2

$1) x^2-5x+6=0 D=25-24=1 x_1=(5+1)/2 = 3; x_2 = (5-1) / 2=2$

$2)x^2-8x+7=0 D=(-8)^2-4*1*7=64-28=36 \sqrt{D}=6 x_1=(-(-8)+6)/2*1=(8+6)/2=7 x_2=(8-6)/2*1=(2)/2=1$

$3)x^2-9x+8=0 D= 81-4*7=49; \sqrt{D} = 7 x_1=(9+7)/2=8 x_2=(9-7)/2=1$

Ответ: 
1) x_1= 3; x_2= 2;
2) x_1= 7; x_2= 1;
3) x_1= 8; x_2= 1.