韩小婧3：(1)4(2x+y)²-9(x+2y)²=[2(2x+y)]²-[3(x+2y)]²=(4x+2y)²-(3x+6y)²=(4x+2y+3x+6y)(4x+2y-3x-6y)=(7x+8y)(x-4y)(2)(x+y)(x+y-2)+1=(x+y)[(x+y)-2]+1=(x+y)²-2(x+y)+1=(x+y...