X.Y是正数,x的平方-Y的平方=2XY,求<X+Y>分之X-Y等于多少
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X^X-Y^Y=2XY其实为(X+Y)(X-Y)=2XY X2为X的平方,Y2为Y的平方把X2-Y2=2XY(x+y)(x+y)=x2+2xy+y2=X2+X2-Y2+Y2=2(x2)(x-y)(x-y)=x2-2xy+y2=x2-x2+y2+y2=2(y2)(x-y)/(x+y)=根号2Y/根号2X=Y/X答案Y/X楼上的答案不对,分给我...
