Question

phân tích thành nhân tử x^2(y+z)+y^2(z+x)+z^2(x+y)+2xyz=0

Answer 1

x^2y+xy^2+x^2z+xz^2+y^2z+yz^2+2xyz 
=x^2y+xy^2+xyz+x^2z+xz^2+xyz+y^2z+yz^2 
=xy(x+y+z)+zx(x+y+z)+yz(y+z) 
=x(y+z)(x+y+z)+yz(y+z) 
=(y+z)(x^2+xy+zx+yz) 
=(x+y)(y+z)(z+x)