(3x-y)(3x+y)+y(x+y);(a+1/2b)(a-1/2b)-(3a-2b)(3a+2b)快点,
问题描述：
(3x-y)(3x+y)+y(x+y);(a+1/2b)(a-1/2b)-(3a-2b)(3a+2b)快点,
答
(3x-y)(3x+y)+y(x+y)=9x²-y²+xy+y²=9x²+xy=x(9x+y)(a+1/2b)(a-1/2b)-(3a-2b)(3a+2b)=a²-b²/4-(9a²-4b²)=-8a²+15b²/4