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24 tháng 8 2019
a.Vì x,y là số nguyên dương
=> 1003 và 2y cũng là số nguyên dương
Vì 2008 là số chẵn
mà 2y cũng là số chẵn
=> 1003x là số chẵn
Vì 1003 là số lẻ
mà 1003x là số chẵn
=> x là số chẵn
=> x chia hết cho 2 (đpcm)
Vậy ta có đpcm
HM
2
19 tháng 1 2017
3x+4y-xy=15
=>y(4-x)+3x=15
=>y(4-x)-3(4-x)(y-3)=15-12=3
=>4-x và y-3 là Ư(3)={-3;-1;1;3}
nếu 4-x=-3 thì x=7
nếu y-3=-1 thì y=2
các trường hợp sau bn tự giari^_^
TH
tìm các số nguyên x,y sao cho
a) (x-2).(3-y)=2
b) | x+3 |+|y-2|=0
d) (x-2).(x-2).(y-3)=-4
e) 3x+4y-xy=15
0
5 tháng 2 2020
a.
xy + 3x - 2y - 6 = 5
=>x(y + 3) - 2(y + 3) = 5
=>(x - 2)(y + 3) = 5.
Vì x, y thuộc Z nên x - 2, y + 3 thuộc Z
=> x - 2, y + 3 thuộc ước nguyên của 5
Lập bảng :
| x - 2 | -5 | -1 | 1 | 5 |
| y + 3 | -1 | -5 | 5 | 1 |
| x | -3 | 1 | 3 | 7 |
| y | -4 | -8 | 2 | -2 |
Vậy ......
b. Làm tương tự câu a.
c. Ta có x + y = 3 và x - y = 15
Bài này là tổng hiệu của cấp 1, áp dụng cách làm đó thì ta được số lớn là x = (3 + 15) : 2 = 9
Số bé là y = 9 - 15 = -6
d. Ta có : |x| + |y| = 1
=>|x| = 1 - |y|
Vì |x|, |y| >= 0 và |x| = 1 - |y| nên 0 =< |x|, |y| =< 1
Vì x, y thuộc Z nên x = 0 thì y = 1 hoặc -1 và ngược lại y = 0 thì x = 1 hoặc -1
14 tháng 1
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TG
9
10 tháng 5 2019
\(x-3-3x-2=-15\)
\(-2x-5=-15\)
\(-2x=-20\)
\(x=10\)
Vậy \(x=10\)
10 tháng 5 2019
\(x-3-\left(3x+2\right)=-15\)
\(1x-3-3x-2=-15\)
\(\left(1-3\right)x-3-2=-15\)
\(-2x=\left(-15\right)+2+3\)
\(-2x=-10\)
\(x=\left(-10\right):\left(-2\right)\)
\(x=5\)
~ Hok tốt ~
CM
1 tháng 4 2017
a) x= 10; y = 25
b) x + 2 y + 10 = 1 5 => ( x = 2).5 = ( y = 10).1=> 5.x + 10 = y + 10
=> 5.x = y mà y – 3.x = 2
Nên x = 1; y = 5
c) x = 20 ; y = 25
DK
0
5 tháng 4 2020
a) 10 - 3x + 3 = -5
=> 13 - 3x = -5
=> 3x = 13 + 5
=> 3x = 18
=> x = 18 : 3 = 6
b) -6|x + 3| = 15 + (-3)
=> -6|x + 3| = 12
=> |x + 3| = 12 : (-6)
=> |x + 3| = -2
=> ko có giá trị x tm
c) 17 - x = 7 - 6x
=> 17 - 7 = -6x + x
=> -5x = 10
=> x = 10 : (-5) = -2
d) Ta có: x + y = 10
x = y => y + y = 10
=> 2y = 10 => y = 5
=> x = 10 - 5 = 5
5 tháng 4 2020
a , x = 6
b , ko có giá trị x thỏa mãn
c , -2
d , 5
k và kb nếu có thể
đề sai bn ơi
\(x-3-\left(3x+2\right)=-15\)
\(\Leftrightarrow x-3-3x-2=-15\)
\(\Leftrightarrow-2x-5=-15\)
\(\Leftrightarrow-2x=-10\)
\(\Leftrightarrow x=5\)