1/7(-2X+3Y)(-2X-3Y)—10(X+Y)的平方

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1/7(-2X+3Y)(-2X-3Y)—10(X+Y)的平方

1/7(-2X+3Y)(-2X-3Y)—10(X+Y)^2 =1/7[-(2X-3Y)(2X+3Y)]-10(X^2+2XY+Y^2) =-1/7(4X^2-9Y^2)-10(X^2+2XY+Y^2) =-4/7*X^2+9/7*Y^2-10*X^2-20XY-10*Y^2 =-74/7*X^2-20XY-61/7*Y^2