原式=(3x+3y)²-(8x+12y)²
=[(3x+3y)+(8x+12y)][(3x+3y)-(8x+12y)]
=-(11x+15y)(5x+9y)
原式=-x(x²-2xy+y²)
=-x(x-y)²在帮我几题 给你分 亲（a^2+b^2)^2-4a^2b^2和a^3-ab^2和3x^3-12x^2y+12xy^2和(x^2-1)^2+6(1-x^2)+9爱你 帮我看看采纳我，重新问