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3. If the seventh term of an AP isand its ninth term is , find iind its o3rd term |
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Answer» Nth term = a+ ( n-1 ) d( where a is the first term, n is the no. of termsand d is the difference between two consecutive terms . ) seventh term = a7 = 1/9 ninth term = a9 =1/7 a7 = a + 6d - ( 1 )a9= a+ 8d - ( 2 )by subtracting ( 1 ) from ( 2 ) (+ )a+ 8d = 1/7 ( +)( - )a+ 6d = 1/9 ( - )= 2d = 2 /63d = 1/63by putting value of d in eq. ( 2 )a + 8 ( 1/63 ) = 1/7a + 8/63 = 1/7a = 1/7 - 8/63a = 1/63 a 63 = a + 62d=1/63 + 62 ( 1 /63 )= 1/63 + 62/63= 1 ans. |
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