请哥哥姐姐帮帮我.1.(a+3分之1)²(a-3之1)²2.(2a+b)²-2(2a+b)(a-2b)+(a-2b)²3.(2x+y)²-4(x-y)(x+2y)

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请哥哥姐姐帮帮我.1.(a+3分之1)²(a-3之1)²2.(2a+b)²-2(2a+b)(a-2b)+(a-2b)²3.(2x+y)²-4(x-y)(x+2y)
请哥哥姐姐帮帮我.
1.(a+3分之1)²(a-3之1)²
2.(2a+b)²-2(2a+b)(a-2b)+(a-2b)²
3.(2x+y)²-4(x-y)(x+2y)

请哥哥姐姐帮帮我.1.(a+3分之1)²(a-3之1)²2.(2a+b)²-2(2a+b)(a-2b)+(a-2b)²3.(2x+y)²-4(x-y)(x+2y)
(a+1/3)²(a-1/3)²
=(a+1/3)(a-1/3)(a+1/3)(a-1/3)
=(a²-1/9)²
=a的4次方 - 2a²/9 + 1/81
(2a+b)² - 2(2a+b)(a-2b)+(a-2b)²
=4a²+4ab+b²-(4a²-6ab-4b²)+a²-4ab+4b²
=a²+6ab+9b²
=(a+3b)²
(2x+y)²-4(x-y)(x+2y)
=4x²+4xy+y²-4(x²+2xy-xy-2y²)
=9y²