greeneyes<3
Find the domain of the expression:
1. 6x^2-9, x>0
2. (x^2-x-12)/(x^2-8+16)
Please show steps or explain them to me! Thank you!
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munaali
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-9
greeneyes<3
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is it like all real numbers, or can you please explain?
munaali
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yes
greeneyes<3
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it still does not make sense, x has to be > 0
munaali
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the real numer has negive
greeneyes<3
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@jim_thompson5910 can you help me with these two problems?
jim_thompson5910
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by default, all polynomials have a domain of the set of all real numbers
jim_thompson5910
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but because it clearly states that x > 0, that means the domain is x > 0, so the domain is the set of positive real numbers
jim_thompson5910
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to find the domain of (x^2-x-12)/(x^2-8x+16), set the denominator equal to zero and solve for x
those two solutions will be values you exclude from the domain
greeneyes<3
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Thank you! Now my answers are:
1. x=all + real numbers
2. x cannot=+ or - 4, and -2
is that right?
jim_thompson5910
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the first one is correct, but the second is not
jim_thompson5910
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hint: x^2 - 8x + 16 factors to (x-4)(x-4)
greeneyes<3
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so x cannot equal 4, or -2 ?
jim_thompson5910
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how are you getting -2?
greeneyes<3
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oh nevermind I see what I was doing wrong, was separating x^2 and -8x and solving them each for -16 separately. So the answer is just x cannot = 4 ?
jim_thompson5910
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bingo, the domain is the set of all real numbers but x cannot equal 4
greeneyes<3
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Okay thank you! :)
jim_thompson5910
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you're welcome