Tìm x, y \(\in\) Z
a) x + y + 2x + 2y = -17
b) x-y = 6 - 2xy
tìm x y thuộc z
a) x+y=xy
b) 2x-xy-2y=3
c) 4x-xy+5y=17
d) 2xy+2n-y=5
a: =>x-xy+y=0
=>x(1-y)+1-y-1=0
=>(x+1)(1-y)=1
=>(x+1)(y-1)=-1
=>\(\left(x+1;y-1\right)\in\left\{\left(-1;1\right);\left(1;-1\right)\right\}\)
=>\(\left(x,y\right)\in\left\{\left(-2;2\right);\left(0;0\right)\right\}\)
b: 2x-xy-2y=3
=>x(2-y)-2y+4=7
=>x(2-y)+2(2-y)=7
=>(x+2)(y-2)=-7
=>\(\left(x+2;y-2\right)\in\left\{\left(1;-7\right);\left(-7;1\right);\left(-1;7\right);\left(7;-1\right)\right\}\)
=>\(\left(x;y\right)\in\left\{\left(-1;-5\right);\left(-9;3\right);\left(-3;9\right);\left(5;1\right)\right\}\)
c: =>x(4-y)+5y-20=-3
=>x(4-y)-5(4-y)=-3
=>(4-y)(x-5)=-3
=>(x-5)(y-4)=3
=>\(\left(x-5;y-4\right)\in\left\{\left(1;3\right);\left(3;1\right);\left(-1;-3\right);\left(-3;-1\right)\right\}\)
=>\(\left(x,y\right)\in\left\{\left(6;9\right);\left(8;5\right);\left(4;1\right);\left(2;3\right)\right\}\)
tìm tập xác định và rút gon : cho B=(2xy/x2-y2+x-y/2x+2y) : x+y/2x+y/y-x
tìm min B = x^2+y^2-2xy+2x-2y+5-2y^2-8y+2015
Ta co :
\(B=y^2-2y\left(1-y\right)+1-2y+y^2+y^2-8y+16+x^2+2x+1+2002\)
B=\(\left(y-1+y\right)^2+\left(y-4\right)^2+(x+1)^2+2002\)
Vi \(\left(2y-1\right)^2;\left(y-4\right)^2;\left(x+1\right)^2\) luon lon hon hoac bang 0 nen
ta co : minB=2002
Tìm x,y thuộc Z
a)49-y^2=6(x-2021)^2
b)x^2 + xy + y^2=2x+y
c)x^2 + xy + y^2=x+y
d)x^2 + 3xy + 3y^2 =3y
e)x^2 - 2xy - 5y^2=y+1
Tìm x,y thuộc Z
a)49-y^2=6(x-2021)^2
b)x^2 + xy + y^2=2x+y
c)x^2 + xy + y^2=x+y
d)x^2 + 3xy + 3y^2 =3y
e)x^2 - 2xy - 5y^2=y+1
Tìm x,y thuộc Z
a)49-y^2=6(x-2021)^2
b)x^2 + xy + y^2=2x+y
c)x^2 + xy + y^2=x+y
d)x^2 + 3xy + 3y^2 =3y
e)x^2 - 2xy - 5y^2=y+1
Tìm x,y thuộc Z
a)49-y^2=6(x-2021)^2
b)x^2 + xy + y^2=2x+y
c)x^2 + xy + y^2=x+y
d)x^2 + 3xy + 3y^2 =3y
e)x^2 - 2xy - 5y^2=y+1
Tìm x,y thuộc Z
a)49-y^2=6(x-2021)^2
b)x^2 + xy + y^2=2x+y
c)x^2 + xy + y^2=x+y
d)x^2 + 3xy + 3y^2 =3y
e)x^2 - 2xy - 5y^2=y+1