Question

if the nth term of an ap be 2n-1,then the sum of its frist n terms will be

Answer 1

Answer:

firstly put N=1,2,3

Step-by-step explanation:

we get 1,3 as a1 and a2

by a2-a1 we find D

3-1=2

so, d is =2

put a and d in sum formula

n/2(2a+(n-1)d)

n/2(2(1)+(n-1)2)

n/2(2+2n-2)

n(2n)/2

so , we get n^2

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