Question

化简:x-y/x+3y÷x^2-y^2/x^2+6xy+9y^2-2y/x+y

Answer 1

原式=(x-y)/(x+3y)×[(x+3y)^2/(x+y)(x-y)]-2y/(x+y)

=(x+3y)/(x+y)-2y/(x+y)

=(x+3y-2y)/(x+y)

=(x+y)/(x+y)

=1