I have a lease on some property that I had a business in. On the lease the length of the lease was written in but I did not sighn and date it. There is other information written in but not signed. I only signed the last page. Is this a legally binding contract?

Was there a place on each page to sign? If not and you only signed at the end because that's where the only signature line is then yes... why wouldn't it be?

Are you implying the landlord wrote in extra conditions after you signed?

If you have a copy of the lease and it's different than what the landlord created after you signed then your copy is the only valid one.