2xy/x^2-y^2+x/x+y, (a^2/a-2-4/a-2)X1/a^2+2a)Xa^2+2a, (1+3/x-
2个回答

解1题:

原式=2xy/(x²-y²)+x/(x+y)

=2xy/[(x+y)(x-y)]+[x(x-y)]/[(x+y)(x-y)]

=[2xy+x(x-y)]/[(x+y)(x-y)]

=(2xy+x²-xy)/[(x+y)(x-y)]

=(x²+xy)/[(x+y)(x-y)]

=[x(x+y)]/(x+y)(x-y)]

=x/(x-y)

解2题:

原式=[a²/(a-2)-4/(a-2)]×[1/(a²+2a)]×(a²+2a)

=[(a²-4)/(a-2)]

=[(a+2)(a-2)]/(a-2)

=a+2

解3题:

原式=[1+3/(x-1)]÷[(x+2)/(x²-1)]

=[(x-1+3)/(x-1)]×[(x²-1)/(x+2)]

=[(x+2)/(x-1)]×[(x+1)(x-1)/(x+2)]

=x+1