Find $sum_1^7 (1+n^2)$ ?

Question

1793 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-12-08T07:13:48

$sum_1^7 (1+n^2)=147$

$sum_1^7 (1+n^2)=7+sum_1^7 n^2$

Using the identity $sum_1^n n^2=(n(n+1)(2n+1))/6$

Hence $sum_1^7 n^2=(7(7+1)(2xx7+1))/6$

$=(7xx8xx15)/6=140$

Hence $sum_1^7 (1+n^2)=147$

Check - $sum_1^7 (1+n^2)=2+5+10+17+26+37+50=147$

Find sum_1^7 (1+n^2)sum_1^7 (1+n^2)?