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General term formula of 0, √ 2,0, √ 2
-2.6.-12.20…… Write through term formula
an=(-1)^n· n(n+1)
The general expressions of 0,6, - 6,18, - 30 and 66. An are derived by using the sequence formula
Please deduce the general term formula of 0, 6, - 6, 18, - 30, 66. An with the formula of equal difference or equal ratio sequence, and the derivation steps. Thank you!
Analysis: 0, 6, - 6, 18, - 30, 66 subtraction between each adjacent two, get 6, - 12,24, - 48,96 (- 1) ^ 0 * 6, (- 1) ^ 1 * 2 * 6, (- 1) ^ 2 * 4 * 6, (- 1) ^ 3 * 8 * 6, (- 1) ^ 4 * 16 * 6 (- 2) ^ 0 * 6, (- 2) ^ 1 * 6, (- 2) ^ 2 * 6, (- 2) ^ 3 * 6, (- 2) ^ 4 * 6 (- 2) ^ 1 * (- 3), (- 2) ^ 2 * (- 3), (- 2) ^ 3 * (- 3)
The expert saved me 1 / 2, - 3 / 10, 5 / 26, - 7 / 50 What's the tenth number
Answer - 19 / 362
Process 1 - 35 - 7 9 - 11 13 - 15 17 - 19 and so on (- 1) ^ (n + 1) * (2n-1)
The following rule is 2 10 26 50: 10-2 = 8 26-10 = 8 * 2 50-26 = 3 * 8. The analogical term 2 + 8 * ((n-1) + (n-2)... + (N-N)) = 2 + 8 * (n ^ 2 / 2-N / 2), so the tenth term equals 2 + 8 * (10 ^ 2 / 2-10 / 2) = 362
So the answer is - 19 / 362
Hope to adopt
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