分解因式:4-12(x-y)+9(x-y)2=______.
4-12(x-y)+9(x-y)2=[2-3(x-y)2]=(2-3x+3y)2.
故答案为:(2-3x+3y)2.
---Do you have New Concept English Ⅵin your shop?
---Yes, but no more than one copy. Would you like to take ______?
A.it B them C.some D.one
采用物理()新技术,在冷作模具表面凃上一薄层1-3μm厚、硬度高达2400HV的(),可使模具寿命成倍提高。