怎么样化简(y+x)²

怎么样化简(y+x)²
怎么样化简(y+x)²

怎么样化简(y+x)²
(y+x)²
=(y+x)(y+x)
=y(y+x)+x(y+x)
=y²+xy+xy+x²
=y²+2xy+x²