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Ex 5.3, 6 - 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, 6 The first and the last term of an AP are 17 and 350 respectively. If the common difference is 9, how many terms are there and what is their sum? Given a = 17 , l = 350, d = 9 We need to find how many terms i.e. n and their sum i.e. Sn We know that an = a + (n − 1)d Putting a = 17 ,an = l = 350, d = 9 350 = 17 + (n − 1) × 9 350 − 17 = (n − 1) × 9 333 = (n − 1) × 9 333/9 = (n − 1) 37 = n − 1 n − 1 = 37 n = 38 To find sum, We use the formula Sum = 𝒏/𝟐 (a + l) Putting n = 38, a = 17, l = 350 Sum = 38/2 (17 + 350) Sum = 19 × 367 Sum = 6973
