Author | Message | Time |
---|---|---|
Probe | can 5^sqrt(3) be solved without a calculator? | May 15, 2006, 9:21 PM |
rabbit | Yes. | May 16, 2006, 12:18 AM |
Probe | how would you go about doing that? | May 16, 2006, 12:34 AM |
shout | 5[sup]√3[/sup] is quite exact. If you go into decimals you will be getting inaccurate answers. | May 16, 2006, 7:58 AM |
rabbit | You can still get an approximate solution. | May 16, 2006, 11:45 AM |
Yoni | I suppose you could develop the Taylor series for 5^sqrt(x) and calculate its value at x = 3. You could also think of a few other approximation tricks. For example, we know that 5^sqrt(3) = sqrt3_root(125). Maybe you have some approximation of sqrt3_root. (I doubt it's easier than what I said above though.) The most obvious is that it's between 5 and 5^2 = 25. It's also between 5^1.7 and 5^1.8, but I don't know how to calculate those. You could combine two taylor series. Calculate x = sqrt(3) and then calculate 5^x @ that x. I don't think the second calculation would be easy though. Just some ideas. | May 17, 2006, 12:27 PM |
rabbit | 1.7 = 1 + 1/7 5[sup]1 + 1/7[/sup] = (5[sup]1[/sup])(5[sup]1/7[/sup]) 5[sup]1/7[/sup] is about 1.26, so 5 * 1.26 = 6.3 1.7 = 1 + 1/8 5[sup]1 + 1/8[/sup] = (5[sup]1[/sup])(5[sup]1/8[/sup]) 5[sup]1/8[/sup] is about 1.22, so 5 * 1.22 = 6.1 6.1 + 6.3 = 12.4 12.4 / 2 = 6.2 Thus your answer is about 6.2 | May 17, 2006, 2:26 PM |
kamakazie | [quote author=rabbit link=topic=14988.msg152629#msg152629 date=1147876001] 1.7 = 1 + 1/7 5[sup]1 + 1/7[/sup] = (5[sup]1[/sup])(5[sup]1/7[/sup]) 5[sup]1/7[/sup] is about 1.26, so 5 * 1.26 = 6.3 1.7 = 1 + 1/8 5[sup]1 + 1/8[/sup] = (5[sup]1[/sup])(5[sup]1/8[/sup]) 5[sup]1/8[/sup] is about 1.22, so 5 * 1.22 = 6.1 6.1 + 6.3 = 12.4 12.4 / 2 = 6.2 Thus your answer is about 6.2 [/quote] 5^sqrt(3) = 16.2424508 | May 17, 2006, 5:08 PM |
rabbit | Well hey, nevermind :P | May 17, 2006, 8:04 PM |
Probe | [quote author=Yoni link=topic=14988.msg152624#msg152624 date=1147868871] I suppose you could develop the Taylor series for 5^sqrt(x) and calculate its value at x = 3. You could also think of a few other approximation tricks. For example, we know that 5^sqrt(3) = sqrt3_root(125). Maybe you have some approximation of sqrt3_root. (I doubt it's easier than what I said above though.) The most obvious is that it's between 5 and 5^2 = 25. It's also between 5^1.7 and 5^1.8, but I don't know how to calculate those. You could combine two taylor series. Calculate x = sqrt(3) and then calculate 5^x @ that x. I don't think the second calculation would be easy though. Just some ideas. [/quote] thanks for the input. could you perhaps explain how you came up with 5^sqrt(3) = sqrt3_root(125)? thanks! | May 18, 2006, 1:27 AM |
Yoni | [quote author=rabbit link=topic=14988.msg152629#msg152629 date=1147876001] 1.7 = 1 + 1/7 1.7 = 1 + 1/8 [/quote] umm ok. [quote author=Probe link=topic=14988.msg152655#msg152655 date=1147915674] thanks for the input. could you perhaps explain how you came up with 5^sqrt(3) = sqrt3_root(125)? thanks! [/quote] Yes. sqrt(3) * sqrt(3) = 3 So, sqrt(3) = 3 / sqrt(3) And, 5^sqrt(3) = 5^(3 / sqrt(3)) = (5^3) ^ (1 / sqrt(3)) = 125^(1 / sqrt(3)) = sqrt3_root(125) | May 19, 2006, 10:39 AM |
rabbit | O shit! It was early............ | May 19, 2006, 11:58 AM |