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Furthermore, how/why do powers of non-integers work? For example, why would (-1)^1.5 be -i?

 Nov 10, 2017
 #1
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(-1) ^ 1.5 is 1.

 

2^0.5 is basically just multiplying 2 0.5 times, which is square root. 

 Nov 10, 2017
 #2
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I'm not sure I understand. 2*0.5 is NOT sqrt(2).

Epic8009  Nov 10, 2017
 #4
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2^0.5   IS   sqrt(2)

Melody  Nov 11, 2017
 #3
avatar+118703 
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(-1)^1.5 

 

(1)1.5=(1)32I can look at this in 2 different ways so lets see what happens.=[(1)3]12or[(1)12]3=[1]12or[1]3=1or[i]3=±iori

 

The only common answer is -i so I guess that is the only correct answer.

 

Maybe another mathematician would like to comment here......

 Nov 11, 2017
 #5
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How did you get from (1)12to 1?

Epic8009  Nov 11, 2017
edited by Epic8009  Nov 11, 2017
 #6
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This is what WolframAlpha says Melody:

 

Alan  Nov 11, 2017
 #7
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(1)121  is a law of fractional exponents. In general terms, xab=bxa=(bx)a

 

Why is this the case? Well, I can attempt to explain it to you.

 

The law of exponents explains how to handle multiplication of exponents with identical bases. 

 

x3x2=x3+2=x5

 

Let's try another example but with fractional exponents.

 

312312=312+12=31=3

 

In this example here, 312 is a number that when multiplied by itself yields 3. That sounds like the definition of the square root, doesn't it? Therefore, 312=3. One can also expound upon this.

 

313313313=313+13+13=31=3
314314314314=314+14+14+14=31=3
315315315315315=315+15+15+15+15=31=3
31x31x31x...31x31x=31x+1x+1x+...+1x+1x=31=3

 

The pattern continues. 313 is a number that when multiplied by itself 3 times yields 3. This is the definition of the cubic root. Then, as you can see, I made a generalization. 31x, when multiplied x times, yields 3. 

TheXSquaredFactor  Nov 11, 2017
 #8
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Thank you!

Epic8009  Nov 11, 2017

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