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Question
The 5th term of an AP is –3 and its common difference is –4. The sum of its first 10 terms is ______.
Options
50
–50
30
–30
MCQ
Fill in the Blanks
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Solution
The 5th term of an AP is –3 and its common difference is –4. The sum of its first 10 terms is –50.
Explanation:
a + 4d = –3 and d = –4.
So, a = 13.
∴ `S_10 = 10/2 [2a + 9d]`
= 5[2 × 13 + 9 × (–4)]
= –50
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