my prof said to me
that when i dont have squares the use this substitution
x1=x1'-x4'
x4=x1'+x4'
so then i woulde have squares and there would be other x1' x4' to link to that square
to complete into (a+b)^2
but here i dont have that
please dont present me something totaly new
i just want the fixup to my prof's method to solve it
thanks