Math Is Fun Forum

plz help me 2 find out the wrong step:all digits are equal just putting values of x,y
s1)  -x.y=-x.y
s2)  x^2-x(x+y)=y^2-y(x+y)
s3)  x^2-2x(x+y)/2+{(x+y)/2}^2 = y^2-2y(x+y)/2+{(x+y)/2}^2
s4)  {x-(x+y)/2}^2 = {y-(x+y)/2}^2
s5)  x-(x+y)/2 = y-(x+y)/2
s6)  x=y