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Alan

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 the roots of 3x^2 -2x-5=0 are alpha and beta find the equation whose roots are alpha^2 and beta^2 (Posted for sacha)

So alpha = 5/3 and beta = -1
To get the (quadratic) equation whose roots are alpha2 and beta2 we construct:
(x - alpha2)*(x-beta2) = 0 or:
x2 -(alpha2+beta2)*x + alpha2*beta2 = 0 прочитайте больше ..
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Alan  22 апр. 2014 г.
 #1
avatar+33669 
+5

There isn't one! 

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31 июл. 2015 г.
 #1
avatar+33669 
+15

Distance and bearing:

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31 июл. 2015 г.
 #1
avatar+33669 
+21

Divisible by 19?

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30 июл. 2015 г.
 #4
avatar+33669 
+5

I think heureka has been misled (in his section (iii)) by the example at : http://wps.prenhall.com/wps/media/objects/3313/3392670/blb2104.html 

 

We are told directly here that Nt/N0 = 0.65, so that's all we need.

 

If the mass of Uranium now is Nt and the original mass was N0 then heureka's formula for original mass should just be:

N0 = Nt + 0.35*N0   which results in N0 = Nt/(1-0.35), so Nt/N0 = (1-0.35) = 0.65.

We don't need the relative atomic masses of U238 and lead206 (we would do if we had the actual masses of U238 and Pb206 now).

 

heureka's expression for Nt/N0 gives a ratio of just over 71%

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29 июл. 2015 г.