Maths唔識抵死題
2010-10-29 1:37 am
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回答 (1)
2010-10-29 2:43 am
✔ 最佳答案
1. Suppose (2x + 3)/(x - 4)^2 = A/(x - 4) + B/(x - 4)^2Then 2x + 3 = A(x - 4) + B
So A = 2 and -4A + B = 3
B = 11
2. (2x + 3)/(x - 4)^2 = 2(x - 4)^-1 + 11(x - 4)^-2
= (-1/2)(1 - x/4)^-1 + (11/16)(1 - x/4)^-2
= (-1/2)(1 + x/4 + x^2/16 + x^3/64 + x^4/256 + ...) + (11/16)(1 + x/2 + 3x^2/16 + x^3/16 + 5x^4/256 + ...)
= 3/16 + 7x/32 + 25x^2/256 + 9x^3/256 + 47x^4/4096 + ...
The expansion valid if 丨x/4丨< 1
丨x丨< 4
-4 < x < 4
參考: me
收錄日期: 2021-04-23 20:46:39
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20101028000051KK00768