Question

Find the sum of AP 3,5,7........ 91

Answer 1

thanks....................

Answer 2

Answer:

2115

Step-by-step explanation:

AP : 3,5,7,....,91

First term = a = 3

Common difference = 5-3 = 7-5 = 2

Formula of nth term = $a_n=a+(n-1)d$

$91=3+(n-1)2$

$88=(n-1)2$

$44=(n-1)$

n = 45

Sum of first n terms = $S_n=\frac{n}{2}(2a+(n-1)d)$

So

$S_{45}=\frac{45}{2}(2(3)+(45-1)(2))$

$S_{45}=2115$