I need help with mathematical induction (1 Viewer)

[ThreeOne]

Use mathematical induction to prove that for all positive integers n:

1. a+ar+ar^2+...+ar^(n-1)= a(r^n-1)/r-1, provided r does not equal to 1

2. a+(a+d)+(a+2d)...+(a+(n-1)d)=1/2 x n(2a+(n-1)d)


I just don't know what to do when there are more than one different... what's it called... letters (?) in the question.

 

[vafa]

I was going to attach my solution by I could not attach them. If you leave an email for me then I will email to you those solutions.

my email address is : Vafairn@aol.com