(3+a)²-(36-4a²)+4(3-a)² x²(3x+5Y)²-y²(5x+3y)² 感激不尽!

问题描述:

(3+a)²-(36-4a²)+4(3-a)² x²(3x+5Y)²-y²(5x+3y)² 感激不尽!

(3+a)^2-(36-4a^2)+4(3-a)^2=(3+a)^2-4(9-a^2)+4(3-a)^2=(3+a)^2-4(3+a)(3-a)+4(3-a)^2=(3+a-2(3-a))^2=(3a-3)^2=9(a-1)^2x^2(3x+5y)^2-y^2(5x+3y)^2=[x(3x+5y)]^2-[y(5x+3y)]^2=[x(3x+5y)+y(5x+3y)][x(3x+5y)-y(5x+...