Question

Question #68654

Answer 1

`5/4(5^171-1)`

Explanation:

Using the polynomial identity

`(x^(n+1)-1)/(x-1)=1+x+x^2+cdots+x^n`

we get at

`5+5^2+cdots+5^171=(5^172-1)/(5-1)-1 = 5/4(5^171-1)`