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perl
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whats the question>

adam32885
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\[\lim_{x \rightarrow 1}\frac{ x1 }{ \sqrt[3]{x+7}2 }\]

adam32885
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I am having trouble with this equation
we are given the hint make the substation x+7=t^3

Azteck
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Rationalise the denominator by multiplying by
\[\frac{ \sqrt[3]{(x+7)^2}+2 }{ \sqrt[3]{(x+7)^2}+2 } \]

Azteck
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Oh now you say you were given that.

Azteck
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\[=\frac{ t^371 }{ t2 }\]

Yahoo!
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x+7=t^3
as x > 1
t > 2

Azteck
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Factorise

Azteck
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And you can get rid of the denominator. Once you do that. Sub back the x's.

adam32885
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so when i make the sub I get \[\lim_{x \rightarrow 1} \frac{ x1 }{ t+2 }\] ?

Azteck
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No you sub the x on the numerator as well.

Yahoo!
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a^3  b^3 = (ab) (a^2 +ab + b^2

Azteck
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\[t^3=x+7\]
make x the subject.
\[x=t^37\]

Azteck
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Now sub the x on the numerator with t^37

adam32885
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oh now i get it. pass the duh stamp

Azteck
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Now you can get rid of that denominator.

Azteck
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Once you do that, remember to replace the t's with
\[\sqrt[3]{x+7}\]

Azteck
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and then you can then sub in x=1 to find the limit.

adam32885
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got it thank you!