The best solution for solving the problem in arithmetic progressions of ncert of exercise 5.3 of math. How i solve this problem In an APii) Given a = 7, a13 = 35, find d and S13.
Share
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Given that, a = 7, a13 = 35
As we know, from the formula of the nth term in an AP,
an = a+(n−1)d,
Therefore, putting the given values, we get,
⇒ 35 = 7+(13-1)d
⇒ 12d = 28
⇒ d = 28/12 = 2.33
Now, Sn = n/2 (a+an)
S13 = 13/2 (7+35) = 273