Х=4,5 или х=-4,5
Х=1,8 или х=-1,8
Х=-25
7,6 : х = 2 1/9 : 2 4/9
38/5 : х = 19/9 : 22/9
19/9Х = 38/5х22/9
19/9Х = 836/45
Х = 836/45 : 19/9 = 836/45 х 9/19
Х = 44/5 = 8,8
3/4(5,1y−3,3)−3/8(2,6y−7,2) =
3/4• 5,1у- 3/4• 3,3- 3/8• 2,6у+ 3/8• 7,2=
0,75•5,1у- 0,75•3,3- 0,375•2,6у+ 0,375•7,2=
3,825у- 2,475- 0,975у+2,7=
2,85у-0,225.
1) x^2+bx+8=0
x1+x2= -b
x1×x2= 8
x= 1; 8
x= -1; -8
x= 2; 4
x= -2; -4
-b= 1+8= 9
b= -9
-b= -1-8= -9
b= 9
-b= 2+4= 6
b= -6
-b= -2-4= -6
b= 6
Ответ: b= -9; 9; -6; 6
2) x^2+bx-18=0
x1+x2= -b
x1×x2= -18
x= 1; -18
x= -1; 18
x= 2; -9
x= -2; 9
x= 3; -6
x= -3; 6
-b= 1-18= -17
b= 17
-b= -1+18= 17
b= -17
-b= 2-9= -7
b= 7
-b= -2+9= 7
b= -7
-b= 3-6= -3
b= 3
-b= -3+6= 3
b= -3
Ответ: b= 17; -17; 7; -7; 3; -3
X+y+z=86
y(x/y+1)+z=86
y(2/9+1)+z=86
11/9y+z=86 (1)
z(11/9y/z+1)=86
z(11/9*6/7+1)=86
z(22/21+1)=86
43/21*z=86
z=86*21/43
z=42
из (1) у=9/11(86-z)=9/11(86-42)=9/11*44=9*4=36
x=86-y-z=86-36-42=8
Ответ. x=8, y=36, z=42