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If nth term of an AP …

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If nth term of an AP is 2n+1.then what is the sum of its first three terms?
  • 3 answers

Yogita Ingle 6 years, 11 months ago

An = 2n + 1
Let n be 1
a1 = 2(1) + 1
a1 = 3
Let n be 2
a2  = 2(2) + 1
= 4 + 1
= 5
Let n be 3
a3 = 2(3) + 1
a3 = 7
a1 + a2 + a3 = 3 + 5 + 7 = 15
 

Honey ☺☺☺ 6 years, 11 months ago

First put n=1and then put n=2 u will get the 1st term and the 2nd term and then find d

Honey ☺☺☺ 6 years, 11 months ago

15
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