Rewrite once even though there are two instances

Stream: new members

[Ben Nale]

Let's say I have the expression (x+3) twice in my goal and I want to replace only one of them with (x+2+1). How do I do this?

[Alex J. Best]

you can use tactic#conv to focus in on the part of the goal you want to rewrite.

[Jalex Stark]

nth_rewrite is relevant, too, I think

[Bryan Gin-ge Chen]

You can also pass an occs option to rw: https://leanprover.zulipchat.com/#narrow/stream/113489-new-members/topic/Sam.20Estep/near/201095954 but nth_rewrite is apparently better.