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In an AP Given a = 7, a13 = 35, find d and S13. - CBSE Class 10 - Mathematics

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Question

In an AP

Given a = 7, a13 = 35, find d and S13.

Solution

Given that, a = 7, a13 = 35

As an = a + (n − 1) d,

∴ a13 = a + (13 − 1) d

35 = 7 + 12 d

35 − 7 = 12d

28 = 12d

d = 7/3

`s_n = n/2[a+a_n]`

`S_13 = n/2[a+a_13]`

`=13/2[7+35]`

`= (13xx42)/2 = 13xx21`

= 273

  Is there an error in this question or solution?

APPEARS IN

 NCERT Solution for Mathematics Textbook for Class 10 (2019 to Current)
Chapter 5: Arithmetic Progressions
Ex. 5.30 | Q: 3.02 | Page no. 112
Solution In an AP Given a = 7, a13 = 35, find d and S13. Concept: Sum of First n Terms of an AP.
S
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