Question

---+n?} is
161.The value of log{ 13+23+33+4+---
a) 2logn+2log(n+1)-2log2
b) logn+2log(n+1)-2log2
c) 2logn+log(n+1)-2log2
d) none of these​

Answer 1

Answer:

none of these

Step-by-step explanation:

since 13 +23+33 +...+n are in AP

use n(2a + (n-1)d)÷2

=n{2×13+(n-1)10}÷2

=n{13+(n-1)5}

=n{8+5n}

now take log

log[n{8+5n}

and now use log property

log(n) +log(8+5n)