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| 1. |
The first term of GP is 1 .the sum ofthe third and fifth term is 90. Find the common ratio of GP |
| Answer» Let first term be a = 1; and common ratio = d;Then, ad² + a d^{4} = 90=> d4 + d² - 90 = 0=> d4 + 10d² - 9d² - 90 = 0=> (d² - 9) (d² + 10) = 0=> d² = 9 {Neglecting -10}=> d = ±3 Hence, the common ratio is ±3..... | |