Example 8 - Find 11th term from last term: 10, 7, 4, .. -62  - Finding nth term from end

  1. Chapter 5 Class 10 Arithmetic Progressions
  2. Serial order wise
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Example 8 Find the 11th term from the last term (towards the first term) of the AP : 10, 7, 4, . . ., 62. AP is 10,7,4, ., 62 Here a = 10 d = 7 10 = 3 First lets find which term is 62 Let an = 62 a + (n 1) d = 62 Putting values 10 + (n 1) ( 3) = 62 10 + n ( 3) 1( 3) = 62 10 3n + 3 = 62 13 3n = 62 3n = 13 62 3n = 75 n = ( 75)/( 3) n = 25 We need to find out 11th term from the last term Last term = 25th Second last term = 25 1 = 24th Third last term = 25 2 = 23rd And so, on So, 11th from last term = (25 10)th term . = 15th term So, we need to find out a15 an = a + (n 1) d Putting values a15 = 10 + (15 1) ( 3) a15 = 10 + (14) ( 3) = 10 42 = 32 So the 11th term from the Last = 15th term from the First = 32

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