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Domain of sqrt(2x^2-7)?

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1 Answer

Hi again M;
√(2x2-7)
As you already know, we cannot square root anything less than zero.  We therefore must find the minimum value of 2x2-7
0≤2x2-7
7≤2x2
7/2≤x2
3.5≤x2
√3.5≤x
-√3.5≥x  Note the fact that because I multiplied the figure by a negative sign, I had to reverse the less than to greater than signage.
domain is (-∞, -√3.5]U[√3.5, +∞)
 
 
 

Comments

Would the domain also include (-√3.5, √3.5) because it could also be any of the values in between and be a real number?
I just updated my )(, parentheses, to ][, brackets, because I realized the same thing.
We cannot render the equation less than zero.  The values between these numbers are NOT included in the domain.
Oh yes, I just realized that. Even though it's negative and positive, there won't be anything in between because it won't fit the sign.