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Ex 5.2, 17 - Chapter 5 Class 10 Arithmetic Progressions
Last updated at Dec. 13, 2024 by Teachoo
Finding nth term from end
Chapter 5 Class 10 Arithmetic Progressions
Concept wise
- Checking if AP or not and finding a, d
- Finding nth term
- Finding n
- Finding AP
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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
- Determining AP and finding sum
Transcript
Ex 5.2, 17 Find the 20th term from the last term of the A.P. 3, 8, 13, …, 253 Given AP 3, 8, 13, …, 253 Now, 20th term from last term of AP 3, 8, 13, …, = 20th term of AP 253, 248, 243, …., 8, 3 Thus, our AP is 253, 248, 243, …., 8, 3 Here a = 253 d = 248 – 253 = −5 We need to find 20th term n = 20 Now, an = a + (n – 1) d Putting values an = 253 + (20 – 1) × (−5) an = 253 + 19 × (−5) an = 253 − 95 an = 158 So the 20th term from the Last is 158
