1\a+1/b=5 求3a+ab+3b\a-2ab+b的值

因为1/a+1/b=(a+b)/ab=5
(a+b)=5ab
代数式=(3（a+b)+ab)/((a+b)-2ab
=(3*5ab+ab)/(5ab-2ab)
=16ab/3ab
=16/3

1/a+1/b=5
(a+b)/ab=5
a+b=5ab,
(3a+ab+3b)/(a-2ab+b)
=[3(a+b)+ab]/(a+b-2ab)
=(15ab+ab)/(5ab-2ab)
=16ab/(3ab)
=16/3