ПО ДЕЙСТВИЯМ ОЧЕНЬ !! 1),2),3) это примеры, не действия
1) (8 4/5-13,8:3 5/6)*12/13=
2)1-0,15:(11/12-0,75)=
3)8,3-(3 5/12-1 1/3):5/12​

1) 3 1/9 : 2 1/3 - 2 5/6 =28/9 * 3/7 - 17/6=4/3-17/6= 8/6-17/6=-3/2=-1.5

2) = 186/17*11/93+5/3=2/17*11/93+5/3=22/17+5/3=66/51+85/51=151/51

3)= 12/7-55/13*26/45=12/7-22/9=108/63-154/63=-46/63

4)= 47/48*27/94-13/16=1/16*9/2-13/16=9/32-13/16=9/32-26/32=-17/32

№ 1.  (8 4/5 - 13,8 : 3 5/6) · 12/13 = 4 целых 4/5 = 4,8.

1) 13,8 : 3 5/6 = 138/10 : 23/6 = 69/5 · 6/23 = (3·6)/(5·1) = 18/5 = 3 3/5

2) 8 4/5 - 3 3/5 = 5 1/5 = 26/5

3) 26/5 · 12/13 = (2·12)/(5·1) = 24/5 = 4 4/5 = 4,8

№ 2.  1 - 0,15 : (11/12 - 0,75) = 0,1.

1) 11/12 - 0,75 = 11/12 - 3/4 = 11/12 - 9/12 = 2/12 = 1/6

2) 0,15 : 1/6 = 3/20 · 6/1 = (3·3)/(10·1) = 9/10 = 0,9

3) 1 - 0,9 = 0,1

№ 3.  8,3 - (3 5/12 - 1 1/3) : 5/12 = 3,3.

1) 3 5/12 - 1 1/3 = 3 5/12 - 1 4/12 = 2 1/12 = 25/12

2) 25/12 : 5/12 = 25/12 · 12/5 = 25/5 = 5

3) 8,3 - 5 = 3,3

x1= - 1

x2= 9

Объяснение:

x^2 - 8x - 9 = 0

x^2 + x - 9x - 9 = 0

x(x+1) - 9(x+1) = 0

(x+1) × (x-9) = 0

x+1=0

x-9=0