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知答案，但唔知steps 點寫?
1) 3^n+1－3^n-1 ／ 2×3^n
=4/3
2a) If n is positive integer, prove that 2^n × 3^n+1 = 3．6^n,
b) Find the value of 2^n × 3^n+1 ／ 6^n-2
=108
F.3Maths Laws of indices
2010-08-15 7:57 pm
回答 (2)
2010-08-15 8:41 pm
✔ 最佳答案
1)3^n+1－3^n-1 ／ 2×3^n= (3^n) (3 - 3^-1) / (2x3^n)= (3 - 3^-1) / 2= (3 - 1/3) / 2= (8/3)/2= 4/32a) 2^n × 3^n+1 = 3．6^nLHS= (2^n) 3^(n+1)= (2^n) (3^n) (3)= 3 ．(2x3)^n = 3 ．6^n= RHSb) 2^n × 3^n+1 ／ 6^n-2By a) ,= (3．6^n) / 6^(n-2)= (3．6^n) / [(6^n)(6^-2)]= 3 / (6^-2)= 3 / (1/36)= 108
2010-08-15 9:31 pm
3^n+1－3^n-1 ／ 2×3^n
3^n(3)-(3^n)(3^-1)/2x3^n
3^n(3-3^-1)/2x3^n
2又3分2/2
8/6
4/3
______________________
2^n × 3^n+1 = 3．6^n
(2^n/6^n)=3/(3^n+1)
1/3^n.....=3/(3^n)(3)
1/3^n.....=1/3^n
____________________
2^n × 3^n+1 ／ 6^n-2
2^nx3^n+1= 3．6^n,
________
3．6^n/(6^n)(6^-2)
3/(1/36)
=108
3^n(3)-(3^n)(3^-1)/2x3^n
3^n(3-3^-1)/2x3^n
2又3分2/2
8/6
4/3
______________________
2^n × 3^n+1 = 3．6^n
(2^n/6^n)=3/(3^n+1)
1/3^n.....=3/(3^n)(3)
1/3^n.....=1/3^n
____________________
2^n × 3^n+1 ／ 6^n-2
2^nx3^n+1= 3．6^n,
________
3．6^n/(6^n)(6^-2)
3/(1/36)
=108
收錄日期: 2021-04-21 22:16:26
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100815000051KK00496