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81^3-27^3/3^7
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12 Sep 2020, 08:02
12 Sep 2020, 08:02
Expert Reply
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Question Stats:
81% (01:01) correct
18% (01:19) wrong based on 33 sessions
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Re: 81^3-27^3/3^7
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28 Sep 2020, 21:40
28 Sep 2020, 21:40
Expert Reply
\(\frac{3^{12}-3^9}{3^7}= \frac{3^9(3^3-1)}{3^7}=3^2 \times 26 = 234\)
Re: 81^3-27^3/3^7
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26 Jul 2021, 09:27
26 Jul 2021, 09:27
1
An alternative solution to this is to realize that 81 and 27 can both be converted to 3^x forms.
81 = 3^4
27 = 3^3
The equation becomes ((3^4)^3 + (3^3)^3) / 3^7 = (3^12 + 3^9) / 3^7. = 3^5 + 3^2.
3^5 + 3^2 = 3^2(3^3 +1) = 234.
**Although not as efficient as the method above ^. I find it important to be able to solve these problems in various ways so you can check your work thoroughly if you have time.
Good luck!
81 = 3^4
27 = 3^3
The equation becomes ((3^4)^3 + (3^3)^3) / 3^7 = (3^12 + 3^9) / 3^7. = 3^5 + 3^2.
3^5 + 3^2 = 3^2(3^3 +1) = 234.
**Although not as efficient as the method above ^. I find it important to be able to solve these problems in various ways so you can check your work thoroughly if you have time.
Good luck!
