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Ex 5.3, 12 - Chapter 5 Class 10 Arithmetic Progressions
Last updated at April 16, 2024 by Teachoo
Determining AP and finding sum
Chapter 5 Class 10 Arithmetic Progressions
Concept wise
- Checking if AP or not and finding a, d
- Finding nth term
- Finding n
- Finding AP
- Finding nth term from end
- Divisible/ multiples
- Statement questions - nth term
- Finding sum of n terms
- Finding number of terms given s
- Given nth term finding s
- Statement questions - Sum of n terms
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Determining AP and finding sum
Transcript
Ex 5.3, 12 Find the sum of first 40 positive integers divisible by 6. Positive integers divisible by 6 are 6, 12, 18, 24,…. Since difference is same, it is an AP We need to find sum of first 40 integers We can use formula Sn = 𝑛/2 (2a + (n – 1) d) Here, n = 40 , a = 6 & d = 12 – 6 = 6 Putting values in formula Sn = 𝒏/𝟐 (2a + (n – 1) d) Sn = 40/2 (2 × 6 + (40 − 1) × 6) Sn = 20 (12 + 39 × 6) Sn = 20 (12 + 234) Sn = 20 × 246 Sn = 4920 Therefore, the sum of first 40 integers divisible by 6 is 4920
