{"id":7037,"date":"2021-10-22T15:46:32","date_gmt":"2021-10-22T10:16:32","guid":{"rendered":"https:\/\/mathemerize.com\/?p=7037"},"modified":"2021-10-25T02:23:42","modified_gmt":"2021-10-24T20:53:42","slug":"if-109-2111108-3112107-10119-k109-then-k-is-equal-to","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/if-109-2111108-3112107-10119-k109-then-k-is-equal-to\/","title":{"rendered":"If \\((10)^9\\) + \\(2(11)^1(10)^8\\) + \\(3(11)^2(10)^7\\) + …… + \\(10(11)^9\\) = \\(K(10)^9\\), then k is equal to"},"content":{"rendered":"
\\(K(10)^9\\) = \\((10)^9\\) + \\(2(11)^1(10)^8\\) + \\(3(11)^2(10)^7\\) + …… + \\(10(11)^9\\)<\/p>\n
K = 1 + 2\\(({11\\over 10})\\)\u00a0 + 3\\(({11\\over 10})^2\\) + ….. + 10\\(({11\\over 10})^9\\)\u00a0 \u00a0 \u00a0 \u00a0……(i)<\/p>\n
\\(({11\\over 10})\\)K = 1\\(({11\\over 10})\\) + 2\\(({11\\over 10})^2\\) + 3\\(({11\\over 10})^3\\) + ….. + 10\\(({11\\over 10})^{10}\\)\u00a0 \u00a0 \u00a0 \u00a0…..(ii)<\/p>\n
On subtracting equation (ii) from (i), we get<\/p>\n
K\\((1 – {11\\over 10})\\) = 1 + \\(({11\\over 10})\\) + \\(({11\\over 10})^2\\) + …. + \\(({11\\over 10})^9\\) – 10\\(({11\\over 10})^{10}\\)<\/p>\n
\\(\\implies\\) K\\(({10 – 11\\over 10})\\) = \\(1[({11\\over 10})^{10} – 1]\\over ({11\\over 10} – 1)\\) – 10\\(({11\\over 10})^{10}\\)<\/p>\n
\\(\\implies\\) – K = 10[10\\(({11\\over 10})^{10}\\) – 10 – 10\\(({11\\over 10})^{10}\\) ]<\/p>\n
\\(\\implies\\) K = 100<\/p>\n
Let \\(a_n\\) be the nth term of an AP. If \\(\\sum_{r=1}^{100}\\) \\(a_{2r}\\) = \\(\\alpha\\) and \\(\\sum_{r=1}^{100}\\) \\(a_{2r-1}\\) = \\(\\beta\\), then the common difference of the AP is<\/a><\/p>\n The sum of first 20 terms of the sequence 0.7, 0.77, 0.777, \u2026\u2026. , is<\/a><\/p>\n If 100 times the 100th term of an AP with non-zero common difference equal to the 50 times its 50th term, then the 150th term of AP is<\/a><\/p>\n If x, y and z are in AP and \\(tan^{-1}x\\), \\(tan^{-1}y\\) and \\(tan^{-1}z\\) are also in AP, then<\/a><\/p>\n