tim cac so x,y,z thuoc Q biet rang (x+y):(5-z):(y+z):(y+9)=3:1:2:5
a, Tim x biet:/x-2/+/3-2x/=2x+1
b, Tim x,y thuoc Z biet:xy+2x-y=5
c, tim x,y,z, biet :2x=3y;4y=5zva 4x-3y+5z=7
tim x;y thuoc z biet:
1/x + 1/y = 1/5
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)
tim x y thuoc z biet (x+y).2=xy
tim x,y thuoc z biet x/5=y/3=z/4 và x-z=7
tim x,y thuộc z biết x/3=y/4=z/5 và 2z+3y+5z=86
tim x,y thuoc Z biet 25-y^2=9(x-2018)^2
tim x thuoc z biet y^2-x^2=102
tim x,y thuoc z biet 25-\(y^2\)=8.(x-2009)^2