
Irakli J.
asked 04/25/19What is the range of the function defined by f(x)=x+2/x
What is the range of the function defined by f(x)=x+2/x :
a) [2,+∞)
b) (-∞,-2√2)∪(2√2,+∞)
c) (-∞,+∞)
d)( -∞,1)∪(1,+∞)
please explain how to find range
2 Answers By Expert Tutors

Tim T. answered 04/25/19
Math: K-12th grade to Advanced Calc, Ring Theory, Cryptography
Greetings! Lets solve this shall we ?
In order to see what the range is, you must graph the function because it cannot be calculated algebraically. When we graph the function, we see it begins coming from negative infinity to -2√2 (-∞, -2√2) because of the lower hump of the graph has a tangent line of y = -2√2 and the top part of the graph has a tangent line at y = +2√2, where the graph continues from (2√2, ∞). The range consists of the set of all y-values where the function exists.
So altogether, the range is (-∞, -2√2] ∪ [2√2, ∞).
I hope this helped!

Doug C.
It seems since 2√2 and its opposite are in the range of function x + 2/x (meaning square bracket) option b) is not correct. Which leads to the conclusion that the function definition was intended to be (x+2)/x?04/25/19

Tim T.
I meant (- infinity, -2root(2)] union [2root(2), infinity) with brackets on the numbers. I believe it was meant to be as it is f(x) = x + (2/x) where the common denominator is x such that f(x) is also (x^2+2) / x.04/25/19

Doug C. answered 04/25/19
Math Tutor with Reputation to make difficult concepts understandable
Finding the range of a function algebraically can be difficult, but not in this case.
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Rich G.
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