(1)(x+y)^2-(x-y)^2
问题描述：
(1)(x+y)^2-(x-y)^2
(2)(-3/5x^2y^3)/(3x^2y)
(3)(10a^4b^3c^2)/(5a^3bc)
(4)(2a+b)^4/(2a+b)^2
(5)(16x^2y^3z+8x^3y^2z)/(8x^2y^2)
(6)(a+3)(a-3)-(a-1)(a+4)
(7)(xy+1)^2-(xy-1)^2
答
1)4xy 2)-1/5y^2 3)2ab^2c 4)(2a+b)^2 5)2yz+xz 6)-3a-5 7)4xy