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10 tháng 1 2018
a) 3 * ( x - 1 ) - ( x - 5 ) = -18
=> 3x - 3 - x + 5 = -18
=> ( 3x - x ) - 3 + 5 = -18
=> 2x + 2 = -18
=> 2x = -18 - 2
=> 2x = -20
=> x = -20 : 2
=> x = -10
b) 5 * ( x + 2 ) - ( 2 * x + 4 ) = -21
=> 5x + 10 - 2x - 4 = -21
=> ( 5x - 2x ) + 10 - 4 = -21
=> 3x + 6 = -21
=> 3x = -21 - 6
=> 3x = -27
=> x = -27 :3
=> x = -9
=> 3x = -39
=> x = -39 : 3
=> x = -13
7 tháng 6 2017
( 2 x y + 2/15 ) x 3 = 4/5
( 2 x y + 2/15 ) = 4/5 : 3
( 2 x y + 2/15 ) = 4/15
2 x y = 4/15 - 2/15
2 x y = 2/15
y = 2/15 :2
y = 1/15
DP
7 tháng 6 2017
(2 x y + 2/15) x 3 = 4/5
2 x y + 2/15) = 4/5 : 3
2 x y + 2/15 = 4/15
2 x y = 4/15 - 2/15
2 x y = 2/15
y = 2/15 : 2
y = 1/15
7/9 x (2 - 1/3 x y) = 14/15
(2 - 1/3 x y) = 14/15 : 7/9
(2 - 1/3 x y) = 6/5
2 - y = 6/5 x 1/3
2 - y = 2/5
y = 2/5 + 2
y = 12/5
4/21 + 5 x y - 8/7 = 1/3
4/21 + 5 x y = 1/3 + 8/7
4/21 + 5 x y = 31/21
5 x y = 31/21 - 4/21
5 x y = 9/7
y = 9/7 : 5
y = 9/35
7/12 x y - 3/12 x y = 5
y x (7/12 - 3/12) = 5
y x 1/3 = 5
y = 5 : 1/3
y = 15
JO
0
NT
0
6 tháng 2 2020
a) \(\left(x-2\right)\left(y-3\right)=14\\ \left(x-2\right)\left(y-3\right)=1\cdot14=14\cdot1=2\cdot7=7\cdot2=\left(-1\right)\left(-14\right)=\left(-14\right)\left(-1\right)=\left(-2\right)\left(-7\right)=\left(-7\right)\left(-2\right)\)
Ta có bảng sau:
| x-2 | 1 | 14 | 2 | 7 | -1 | -14 | -2 | -7 |
| x | 3 | 16 | 4 | 9 | 1 | -12 | 0 | -5 |
| y-3 | 14 | 1 | 7 | 2 | -14 | -1 | -7 | -2 |
| y | 17 | 4 | 10 | 5 | -11 | 2 | -4 | 1 |
Vậy \(\left(x;y\right)\in\left\{\left(3;17\right);\left(16;4\right);\left(4;10\right);\left(9;5\right);\left(1;-11\right);\left(-12;2\right);\left(0;-4\right);\left(-5;1\right)\right\}\)
b) \(\left(x-5\right)\left(y+5\right)=21\\ \left(x-5\right)\left(y+5\right)=1\cdot21=21\cdot1=3\cdot7=7\cdot3=\left(-1\right)\left(-21\right)=\left(-21\right)\left(-1\right)=\left(-3\right)\left(-7\right)=\left(-7\right)\left(-3\right)\)
Ta có bảng sau:
| x-5 | 1 | 21 | 3 | 7 | -1 | -21 | -3 | -7 |
| x | 6 | 26 | 8 | 12 | 4 | -16 | 2 | -2 |
| y+5 | 21 | 1 | 7 | 3 | -21 | -1 | -7 | -3 |
| y | 16 | -4 | 2 | -2 | -26 | -6 | -12 | -8 |
Vậy \(\left(x;y\right)\in\left\{\left(6;16\right);\left(26;-4\right);\left(8;2\right);\left(12;-2\right);\left(4;-26\right);\left(-16;-6\right);\left(2;-12\right);\left(-2;-8\right)\right\}\)
c) \(x\left(y-1\right)-6\left(y-1\right)=25\\ \left(x-6\right)\left(y-1\right)=25\\ \left(x-6\right)\left(y-1\right)=1\cdot25=25\cdot1=5\cdot5=\left(-1\right)\left(-25\right)=\left(-25\right)\left(-1\right)=\left(-5\right)\left(-5\right)\)
Ta có bảng sau:
| x-6 | 1 | 25 | 5 | -1 | -25 | -5 |
| x | 7 | 31 | 11 | 5 | -19 | 1 |
| y-1 | 25 | 1 | 5 | -25 | -1 | -5 |
| y | 26 | 2 | 6 | -24 | 0 | -4 |
Vậy \(\left(x;y\right)\in\left\{\left(7;26\right);\left(31;2\right);\left(11;6\right);\left(5;-24\right);\left(-19;0\right);\left(1;-4\right)\right\}\)
(x+2)(y-1)=133
=>\(\left(x+2;y-1\right)\in\left\{\left(1;133\right);\left(133;1\right);\left(-1;-133\right);\left(-133;-1\right);\left(7;19\right);\left(19;7\right);\left(-7;-19\right);\left(-19;-7\right)\right\}\)
=>\(\left(x;y\right)\in\left\{\left(-1;144\right);\left(131;2\right);\left(-3;-132\right);\left(-135;0\right);\left(5;20\right);\left(17;8\right);\left(-9;-18\right);\left(-21;-6\right)\right\}\)
b: (x-5)(y-2)=21
=>\(\left(x-5;y-2\right)\in\){(1;21);(21;1);(-1;-21);(-21;-1);(3;7);(7;3);(-3;-7);(-7;-3)}
=>\(\left(x;y\right)\in\){(6;23);(26;3);(4;-19);(-16;1);(8;9);(12;5);(2;-5);(-2;-1)}