tim x biet
\(xy+2x+y=-1\)1
a,tim x biet |x-2|+|3-2x|=2x+1
b,tim x,y thuoc Z biet xy+2x-y=5
c, tinh A=(1-1/15)(1-1/21)(1-1/28).....(1-1/210)
Bai 1 : Tim cac so nguyen x , y biet :
a, x +xy + y = 9
b, xy - 2x -3y = 5
c, xy - 2x + 5y = 2
a, x + xy + y = 9
=>xy + x+y+1=10
=>x.(y+1)+(y+1)=10
=>(x+1).(y+1)= 10.1 = 1.10 = 2.5 = 5.2 = (-10).(-1) = (-1).(-10) = (-2).(-5) = (-5).(-2)
ta có bảng các trường hợp sau
x+1 | 1 | 10 | 2 | 5 | -10 | -1 | -2 | -5 |
y+1 | 10 | 1 | 5 | 2 | -1 | -10 | -5 | -2 |
x | 0 | 9 | 1 | 4 | -11 | -2 | -3 | -6 |
y | 9 | 0 | 4 | 1 | -2 | -11 | -6 | -3 |
vậy
bn tich cho mk nha
tim cac so nguyen duong x,y biet
1/2x+1/2y+1/xy=1/2
\(\dfrac{1}{2x}+\dfrac{1}{2y}+\dfrac{1}{xy}=\dfrac{1}{2}\)
\(\dfrac{y}{2xy}+\dfrac{x}{2xy}+\dfrac{2}{2xy}=\dfrac{xy}{2xy}\)
=> x + y + 2 = xy
x + y - xy = -2
x.( 1 - y ) + y = -2
x.( 1 - y ) - ( 1 - y ) = -2 - 1
( 1 - y ).( x - 1 ) = -3
- ( y - 1 ).( x - 1) = -3
=> ( y - 1 ).( x - 1 ) = 3
=> ( y - 1 ) ; ( x - 1 ) \(\in\) Ư( 3 ) = { 1; -1; 3; -3 }
Ta có bảng sau
y - 1 | 1 | -1 | 3 | -3 |
y | 2 | 0 | 4 | -2 |
x - 1 | 3 | -3 | 1 | -1 |
x | 4 | -2 | 2 | 0 |
Vậy ( x ; y ) \(\in\) { ( 4 ; 2 ); ( -2 ; 0 ); ( 2; 4 ); ( 0; -2 ) }
Bai 1 : Tim cac so nguyen x , y biet :
a, xy - 2x -3y = 5
b, xy - 2x + 5y = 2
xy-2x-3y+6=5+6
x(y-2)-3(y-2)=5+6
(x-3)(y-2)=11
(x-3)(y-2)=1.11;11.1
nếu (x-3)(y-2)=1.11=> x=4 và y=13
nếu (x-3)(y-2)=11.1=>x=14 và y=3
câu b tương tự
xy-2x+5y-10=2-10
x(y-2)+5(y-2)=-8
.....
nhớ tick nha
Nguyễn Thùy Linh sai vì 3y+6=3(y+2) chứ ko phải 3y+6=3(y-2)
Tim x,y biet
a)(2x +1)(3y-2)=55
b)(x+1)(xy-1)=3
Tim so nguyen x,y biet
(x+1)^2+(y-1)^2=0
(x+3)×(y+1)=3
xy-2x=5
(x+3).(y+1)=3
--->x+3,y+1 thuộc Ư(3)={1,3,-1,-3}
Ta có bảng sau
x+3 1 -1
y+1 3 -3
y 2 -4
x -2 -4
--->(x,y) thuộc(-2,2),(-4,-4)
tim x biet x-y=xy-1
cm x^3 -x^2 -2x^2 +2x chia het cho 6
tim x;y biet
x-y=xy-1
cho x thuoc tap so nguyen biet
x^3 -x^2 -2x^2 +2x chia het cho 6
tim x va y biet : xy – 2x + y = 15
xy-2x+y=15
<=.xy-2x+y-2=13
<=>x(y-2)+(y-2)=13
<=>(x+1)(y-2)-13=0
<=>(x+1)(y-2)-13=-13.1=13.(-1)
x+1 -13 1 13 -1
y-2 1 -13 -1 13
x -14 0 12 -2
y 3 -11 1 15
vậy pt có 4 nghiệm:
(1)x=-14 ; y=3
(2)x=0 ; y=-11
(3)x=12 ; y=1
(4)x=-2 ; y=15