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| 1. |
Find the 25th term of the A.P. -5, -5/2, 0, 5/2 |
| Answer» The given Arithmetic progression is\xa0{tex} - 5 , \\frac { - 5 } { 2 } , 0 , \\frac { 5 } { 2 } ,{/tex}.....Its first term a = -5 and common difference d =\xa0{tex}\\left( \\frac { 5 } { 2 } - 0 \\right) = \\frac { 5 } { 2 }.{/tex}Therefore,\xa0a = -5 and\xa0{tex}d = \\frac { 5 } { 2 }.{/tex}{tex}\\Rightarrow{/tex}\xa0T25 = a + (25-1)d{tex}= a + 24 d \\\\= ( - 5 ) + \\left( 24 \\times \\frac { 5 } { 2 } \\right)\\\\ = - 5 + 60 = 55.{/tex}Hence, 25th term = 55. | |