Find the smallest value of this function.

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Discussion Overview

The discussion revolves around finding the smallest value of the function f(x) = x^2 - 3x + sqrt(x-3) - sqrt(x+3). Participants explore various methods to approach the problem, including algebra, geometry, and calculus, while also addressing the implications of the function's domain and behavior.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant questions the notation used in the function, suggesting there may be confusion regarding the variable 'n' versus 'x'.
  • Another participant points out that the function has complex roots due to the square roots involved, raising the question of what is meant by the "smallest value"—whether it refers to real or imaginary numbers.
  • A participant asserts that the function is only defined for x >= 3 and claims it is an increasing function, suggesting that the smallest value occurs at x = 3.
  • There is a claim that the smallest value at x = 3 is f(3) = -sqrt(6), but this is presented without further elaboration on the calculations involved.
  • One participant expresses a desire for clarification or a step-by-step solution to the problem.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the problem, particularly regarding the concept of "smallest value" in relation to complex numbers. While there is some agreement on the function's domain, the discussion remains unresolved regarding the overall approach to finding the smallest value.

Contextual Notes

The discussion highlights limitations related to the function's domain and the implications of complex roots, as well as the need for clarity in defining what is meant by "smallest value." There are also unresolved mathematical steps in deriving the smallest value.

PrudensOptimus
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f(x) = x^2 - 3x + sqrt(x-3) - sqrt(x+3)

Using algebra, geometry, calculus, whatever you want, but do not use a calculator :p

Also must show work.

Very interesting math problem I saw on the web.
 
Last edited:
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what is with the 'n'. Isn't it supposed to be an x.

The function has complex roots because of the sqrt's. So want do you mean by smallest value. Smallest real number or smallest imaginary number?
 
both.
 
Actually, neither the question by dduardo, "The function has complex roots because of the sqrt's. So want do you mean by smallest value. Smallest real number or smallest imaginary number?", nor the response by PrudensOptimus, "Both" make any sense.

In the first place, the question asked about the smallest value of the function- it didn't say anything about roots. Secondly, the complex numbers cannot be ordered so it never makes sense to ask about the "smallest" complex number.

The function f(x)= x^2 - 3x + sqrt(x-3) - sqrt(x+3)
is only defined for x>= 3 and it's pretty easy to see that it is an increasing function. The smallest value occurs at x= 3 and is
f(3)= 9- 9+ sqrt(0)- sqrt(6)= - sqrt(6).
 
:) I got it right yay

it is from the restriction 4sqrt[(x-3)(x+3)].
 
someone show me the work for this please, I am a dumb butt..
 

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