x^2-y^2/x^2+2xy+y^2-x+y/x-y,其中x=1,y=-3
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x^2-y^2/x^2+2xy+y^2-x+y/x-y,其中x=1,y=-3
带数求值!^-^
下列运算正确的是 ( )
A.a/a-b-b/b-a=1 B.m/a-n/b=m-n/a-b
C.b/a-b+1/a=1/a D.2/a-b-a+b/a^2-b^2=1/a-b
带数求值!^-^
下列运算正确的是 ( )
A.a/a-b-b/b-a=1 B.m/a-n/b=m-n/a-b
C.b/a-b+1/a=1/a D.2/a-b-a+b/a^2-b^2=1/a-b
x^2-y^2/x^2+2xy+y^2-x+y/x-y
=(x+y)(x-y)/(x+y)²-(x+y)/(x-y)
=(x-y)/(x+y)-(x+y)/(x-y)
=-4xy/(x²-y²)
当x=1,y=-3时
原式=12/(1-9)=-3/2
D.2/a-b-a+b/a^2-b^2=1/a-
=(x+y)(x-y)/(x+y)²-(x+y)/(x-y)
=(x-y)/(x+y)-(x+y)/(x-y)
=-4xy/(x²-y²)
当x=1,y=-3时
原式=12/(1-9)=-3/2
D.2/a-b-a+b/a^2-b^2=1/a-
x+y)(x-y)+(x-y)^2-(6x^2y-2xy^2)/2y,其中x=-2,y=1/3
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