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| 1. |
What is the common difference of an AP in which a21-a7. 84 |
| Answer» Let {tex}a{/tex} be first term and {tex}d {/tex} be the common difference.{tex}a_{21} - a_{7} = 84{/tex}{tex}a + (21 - 1)d - a + (7 - 1)d = 84{/tex}{tex}a + 20d - a - 6d = 84{/tex}{tex}14d = 84{/tex}{tex}d = 6{/tex}Therefore, common difference is 6. | |