simplify them
1).............2^2n+1+7(2^n) / 4(2^n) = ????
2).............9(4^n)-3(2^n+1) / 5(2^n-1) = ???????????
thx
index F3 maths~~help~~~~~~
2011-06-12 8:11 pm
回答 (1)
2011-06-13 1:15 am
✔ 最佳答案
1)2^(2n + 1) + 7(2^n) / 4(2^n)
= 2^2n * 2 + 2^n * 7 / (2^n * 4)
= 2^n * 2^n * 2 + 2^n * 7 / (2^n * 4)
= 2^n(2*2^n + 7) / 2^n * 4
= (2 * 2^n + 7) / 4
= 2^n / 2 + 7/4
2)
9(4^n) - 3[2^(n + 1)] / 5[2^(n - 1)]
= 9(4^n) - 3 * 2^n * 2 / (5 * 2^n / 2)
= 9 * 2^2n - 6 * 2^n / (2.5 * 2^n)
= 36 * 2^n - 6 * 2^n / 2.5 * 2^n
= 30 * 2^n / 2.5 * 2^n
= 12
收錄日期: 2021-04-13 18:01:36
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https://hk.answers.yahoo.com/question/index?qid=20110612000051KK00336