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Class 10 (Old)

Course: Class 10 (Old) > Unit 5

Lesson 4: Sum of first n terms of an AP
Math
Class 10 (Old)
Arithmetic progressions
Sum of first n terms of an AP
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Sum of n terms (advanced)

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Problem

The sum of the first 6 terms of an arithmetic progression is 138.
The 9, start superscript, start text, t, h, end text, end superscript term and the 14, start superscript, start text, t, h, end text, end superscript term are the ratio 9, colon, 13.
Find the first term, a, start subscript, 1, end subscript.
a, start subscript, 1, end subscript, equals
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3, slash, 5
  • a simplified improper fraction, like 7, slash, 4
  • a mixed number, like 1, space, 3, slash, 4
  • an exact decimal, like 0, point, 75
  • a multiple of pi, like 12, space, start text, p, i, end text or 2, slash, 3, space, start text, p, i, end text
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