25x^4++10x²+1
=(5x²)²+2×5x²+1
=(5x²+1)²这个呢-x平方-4y平方+4xy和3ax平方+6axy+3ay平方-x²-4y²+4xy=-(x²+4y²-4xy)=-(x-2y)²3ax²+6axy+3ay²=3a(x²+2xy+y²)=3a(x+y)²