Order the given radical numbers

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The discussion focuses on ordering the radical expressions x = √[7]{13} + √[6]{13}, y = √[5]{13} + √[8]{13}, and z = √[3]{13} + √[10]{13}. Participants explore various mathematical approaches, including the use of derivatives and properties of functions, to determine the relationships between these expressions. It is established that the function f(t) = 13^(1/t) is decreasing for t < 6.5 and increasing for t > 6.5, leading to the conclusion that z > y > x. The conversation emphasizes the symmetry of the function and the behavior of its derivatives to support the ordering of the radicals. Overall, the conclusion is reached that z is the largest, followed by y, and then x.
  • #31
how's this?
A = 1/5 - 1/7 > 1/6 - 1/8 = a, hence (13)^(1/5) - (13)^(1/7)

=[(13)^(1/7][13^A - 1] > [(13)^(1/8)][13^a - 1]

= (13)^(1/6) - (13)^(1/8), hence

y = (13)^(1/5) + (13)^(1/8) > (13)^(1/6) + (13)^(1/7) = x.

just elementary precalculus, unless I made a mistake, which I frequently do in this realm.

edit: I guess this is basically the same as pasmith's (more general) solution in the previous post.
 
Last edited:

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