Question

Find the sum of first twenty five terms of AP series whose nth term is n+7/4 a) 105 b) 125 c) 115 d) 135​

Answer 1

Answer:

The correct answer is a) 105.

Step-by-step explanation:

We have,

nth term = $\frac{n+7}{4}$

∴1st term(a1) = $\frac{1+7}{4}$ = 2

∴25th term(a25) = $\frac{25+7}{4}$ = 8

Now,

Sum of 1st 25 terms in AP = $\frac{n(a_{1}+a_{25}) }{2}$ =  $\frac{25*(2+8) }{2}$ = 105