DKXD:x#2;3;4;5
[(x+3/x+2)-1]-[(x+4/x+3)-1]=[(x+5/x+4)-1]-[(x+6/x+5)-1]
<=>(1/(x+2)-(1/(x+3)=(1/(x+4)-(1/(x+5)
=>(x+3)(x+4)(x+5)-(x+2)(x+4)(x+5)=(x+2)(x+3)(x+5)-(x+2)(x+3)(x+4)
<=>(x+4)(x+5)[x+3-x-2]=(x+2)(x+3)[x+5-x-4]
<=>(x+4)(x+5)=(x+2)(x+3)
<=>x^2+9x+20-x^2-5x-6=0
<=>4x-14=0=>x=14/4=7/2( thõa mãn dkxd )