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The sum of the first 14 terms of an AP is 1050 and the first term is 10.
Using the sum formula, find the 20th term of this AP.

Class 10Sum of n Terms of an APAlgebra — Sequences

A180
B220
C200
D400

Step-by-Step Solution

1050 = \frac{14}{2} [2 (10) + 13 d] \Rightarrow 1050 = 7 [20 + 13 d] \Rightarrow 150 = 20 + 13 d \Rightarrow 13 d = 130 \Rightarrow d = 10. a_{20} = 10 + 19 (10) = 200

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Answer: C) 200

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