Domain of f(x) for √[(2x+1)/x3-3x2+2x]: Homework Solution and Explanation

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The domain of the function f(x) = √[(2x+1)/(x³-3x²+2x] requires that the expression inside the square root is non-negative. This leads to the conditions x³-3x²+2x > 0 and 2x+1 ≥ 0. The correct domain is (-∞, -1/2] ∪ (0, 1) ∪ (2, ∞), as the numerator and denominator must have the same sign, allowing for specific intervals where the function is defined. Misinterpretation of the conditions led to confusion regarding the domain boundaries.

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Homework Statement



f(x)= √[(2x+1)/x3-3x2+2x]

Homework Equations





The Attempt at a Solution



here
For f(x) to exist
x3-3x2+2x >0

and 2x+1≥0
by solving this i found that x \in [-\frac{1}{2},-∞]\bigcup[2,∞]
but the answer given is (-∞,-1/2]\bigcup(0,1)(2,∞)


so please anybody can explain why that is so


thanks
 
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What about 2x+1 <= 0, x3-3x2+2x < 0?

There are brackets missing in the problem statement.
 
nil1996 said:

Homework Statement



f(x)= √[(2x+1)/x3-3x2+2x]
I think you mean √[(2x+1)/(x3-3x2+2x)]

Homework Equations


The Attempt at a Solution



here
For f(x) to exist
x3-3x2+2x >0

and 2x+1≥0
No, the numerator and denominator do NOT have to both be positive. What is true is that the fraction cannot be negative which means that, as long as the numerator is not 0, they must have the same sign. That is, either x3-3x2+2x >0 and 2x+1≥0 OR x3-3x2+2x <0 and 2x+1< 0.

by solving this i found that x \in [-\frac{1}{2},-∞]\bigcup[2,∞]
but the answer given is (-∞,-1/2]\bigcup(0,1)(2,∞)so please anybody can explain why that is sothanks
 

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