Consider given the given given polynomials,
⇒x(x+y−r),y(x−y+r),z(x−y−z)
Now,
⇒⇒x(x+y−r)+y(x−y+r)+z(x−y−z)
⇒(x2+xy−xr)+(yx−y2+yr)+(zx−zy−z2)
⇒x2−y2−z2+xy−xr+yx+yr+zx−zy
Hence, this is the answer,