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\(xy+14+2y+7x=-10\)
\(\Rightarrow xy+7x+7y=-24\)
\(\Rightarrow x\left(y+7\right)+7y=-24\)
\(\Rightarrow x\left(y+7\right)+7y+49=-24+49\)
\(\Rightarrow x\left(y+7\right)+7\left(y+7\right)=25\)
\(\Rightarrow\left(x+7\right)\left(y+7\right)=25\)
\(\Rightarrow\left(x+7\right);\left(y+7\right)\inƯ\left(25\right)=\left\{\pm1;\pm5;\pm25\right\}\)
Xét bảng
| x+7 | 1 | -1 | 5 | -5 | 25 | -25 |
| y+7 | 25 | -25 | 5 | -5 | 1 | -1 |
| x | 6 | -8 | -2 | -12 | 18 | -32 |
| y | 18 | -32 | -2 | -12 | 6 | -8 |
Vậy.........................
\(xy+x+y=2\)
\(\Rightarrow x\left(y+1\right)+\left(y+1\right)=2+1\)
\(\Rightarrow\left(x+1\right)\left(y+1\right)=3\)
\(\Rightarrow\left(x+1\right);\left(y+1\right)\inƯ\left(3\right)=\left\{\pm1;\pm3\right\}\)
Xét bảng
| x+1 | 1 | -1 | 3 | -3 |
| y+1 | 3 | -3 | 1 | -1 |
| x | 0 | -2 | 2 | -4 |
| y | 2 | -4 | 0 | -2 |
Vậy.....................................
\(xy-10+5x-3y=2\)
\(\Rightarrow xy-5x-3y=12\)
\(\Rightarrow x\left(y-5\right)-3y+15=12+15\)
\(\Rightarrow x\left(y-5\right)-3\left(y-5\right)=27\)
\(\Rightarrow\left(x-3\right)\left(y-5\right)=27\)
\(\Rightarrow\left(x-3\right);\left(y-5\right)\inƯ\left(27\right)=\left\{\pm1;\pm3;\pm9;\pm27\right\}\)
Tự xét bảng như trên
\(xy-1=3x+5y+4\)
\(\Rightarrow xy-3x-5y=4+1\)
\(\Rightarrow x\left(y-3\right)-5y+15=1+4+15\)
\(\Rightarrow x\left(y-3\right)-5\left(y-3\right)=20\)
\(\Rightarrow\left(x-5\right)\left(y-3\right)=20\)
\(\Rightarrow\left(x-5\right)\left(y-3\right)\inƯ\left(20\right)=\left\{\pm1;\pm2;\pm4;\pm5;\pm10;\pm20\right\}\)
Xét bảng
| x-5 | 1 | -1 | 2 | -2 | 4 | -4 | 5 | -5 | 10 | -10 | 20 | -20 |
| y-3 | 20 | -20 | 10 | -10 | 5 | -5 | 4 | -4 | 2 | -2 | 1 | -1 |
| x | 6 | 4 | 7 | 3 | 9 | 1 | 10 | 0 | 15 | -5 | 25 | -15 |
| y | 23. | -17 | 13 | -7 | 8 | -2 | 7 | -1 | 5 | 1 | 4 | 2 |
Vậy......................................
a, (-72).(15 - 49) + 15.(-56 + 72)
= -72 . 15 + 72.49 - 15.56 + 15.72
= (-72.15 + 15.72) + (72.49 - 15.56)
= 3528 - 84
= 2688
1b, 1532 + (-186) + (-1432) + (-14) + 123
= (1532 - 1432) - (186 + 14) + 123
= 100 - 200 + 123
= 223 - 200
= 23
1532+(-186)+(-1432)-14+123
=1532+(-186)+(-1432)+(-14)+123
=[(-186)+(-14)]+[1532+(-1432)]+123
= (-200) + 100 +123
= (-100) + 123
= 23
nhớ tick cho mình nhé các bạn
\(-3+x=5-\left(-7\right)\)
\(\Leftrightarrow-3+x=5+7\)
\(\Leftrightarrow-3+x=12\)
\(\Leftrightarrow x=12+3\)
\(\Leftrightarrow x=15\)
Vậy x= 15
\(x-2=2x-7\)
\(\Leftrightarrow x-2+7=2x\)
\(\Leftrightarrow x-\left(2-7\right)=2x\)
\(\Leftrightarrow2-7=x-2x\)
\(\Leftrightarrow-5=-x\)
\(\Leftrightarrow x=5\)
Vậy x= 5
Câu 1 :
a) 1532 + ( - 186 ) + ( - 1432 ) - 14 + 123
= 1532 - 186 - 1432 - 14 + 123
= ( 1532 - 1432 ) - ( 186 + 14 ) + 123
= 100 - 200 + 123
= -100 + 123
= -23.
b) -47.69 + 31.(-47)
= -47 . ( 69 + 31 )
= -47 . 100 = -4700
Câu 2
a) x + 10 = -14
x = -14-10 = -24
b ) 5x-12=48
5x = 48+12=60
x=60:5=12
Câu 1:
a) 1532 +(-186) +(-1432)-14+123
=1532+(-1432)+[(-186)-14]+123
= 100 + (-200) +123
=23
b)-47.69 +31.(-47)
=-47(69+31)
= -47.100
=-4700
Câu 2:
a) x+10=-14
x=-14-10
x=-24
b)5x-12=48
5x=48+12
5x=60
x=60:5
x=12
Tick cho mình nha bạn!