Board 8 > How do you find the domain of this function?

(+) Yeah! (+)

f(x) = 5 / (5x^2 - 8)

so i set the bottom part = 0

i got x = (2 radical 10) / 5

How do I express this in interval notation? Isn't it just x doesn't equal (2 radical 10) / 5?

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KA POWIE

x doesn't equal plus/minus 2sqrt(10)/5

EDIT: This is a domain that you don't express in interval notation. Also, it's plus/minus because when you take the square root of something (like solving x^2=?) you cannot forget that the answer could also be negative.

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"(Use symbolic notation and fractions where needed. Give your answers as intervals in the form (*,*). Use symbol for infinity, and for combining intervals, and appropriate type of parenthesis "(", ")", "[" or "]" depending on whether the interval is open or closed.)"

does "not equal sign" mean that?

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KA POWIE

x= +/- 1,26

assuming you have everything correct, I think.

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How'd you get that?

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KA POWIE

When the domain is just +/- something you most certainly do not need to put it in interval notation. Never in my days have I seen [a,a].

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this is an online HW so idk maybe that's why it's whack. how'd you get +/- 1,26?

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KA POWIE

If you don't want to take the chance, I guess you could write:

[-2sqrt(10)/5,-2sqrt(10)/5] U [2sqrt(10)/5,-2sqrt(10)/5]

That honestly looks may worse than x != +/-2sqrt(10)/5

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2sqrt(10)/5 = 1.26...

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i'm gonna try putting +- the radical answer.. lets see..

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KA POWIE

ok im confused one of them wanted some long thing consisting of negative ininfity to negative radical, negaive radical to positive radical, and radical to infinity, while another was just from negative inifinity to infinifty.

so what would the deal be with this one:

7 / 2x^2 - 3

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KA POWIE

I get x = radical 3/2 .. but how do I display my answer?

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KA POWIE