Math, asked by sitishaggarwal7672, 1 year ago

Maths class 10 if nterm of an ap is 2n+1 what is the sum of its first three terms

Answers

Answered by nikhil3697
1

if an = 2n+1

then

a1=2×1+1=3

a2=2×2+1=5

a2=7

therefore,

d=a2-a1=5-3=2

now,

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

s=3/2(6+4)

s=5×3

s=15

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