Contact us
Choose a category below so we can get back to you as quickly as possible.
A3=S2+1=A1+A2+1 A4=S3+1=A1+A2+A3+1 A4-A3=A3 2a3=a4 a4/a3=2 所以公比q=2
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.