Mathematics
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OpenStudy (anonymous):
solve this limit:
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OpenStudy (anonymous):
\[\lim_{x \rightarrow -1}\frac{ 2x^2+5x+3 }{ x-1 }\]
hartnn (hartnn):
can u factor
2x^2+5x+3 ?
zepdrix (zepdrix):
Just plug in -1 silly burh! :)
OpenStudy (anonymous):
2x^2+2x+3x+3
OpenStudy (anonymous):
just do a direct substitution.....
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OpenStudy (anonymous):
i get 0/0 if i do direct subs.
zepdrix (zepdrix):
Oh maybe you wrote something down wrong then, cause it looks like you get -2 in the bottom
OpenStudy (anonymous):
the denominator does not end up with 0....
hartnn (hartnn):
now take 2x common from 1st 2 terms of 2x^2+2x+3x+3
hartnn (hartnn):
does x->1 ??
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OpenStudy (anonymous):
\[\lim_{x \rightarrow -1} \frac{ 2x^2+5x+3 }{x+1 }\]
sorry for the typo :$
hartnn (hartnn):
ok, factor the numerator
OpenStudy (anonymous):
2x^2+2x+3x+3
hartnn (hartnn):
then?
OpenStudy (anonymous):
i dont know what's next. Substitution ? :S
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hartnn (hartnn):
take 2x common from 2x^2+2x
what u get ?
OpenStudy (anonymous):
2(x^2+x)
OpenStudy (anonymous):
*** 2x(x+1)
hartnn (hartnn):
take 3 common from 3x+3
OpenStudy (anonymous):
+3(x+1)
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hartnn (hartnn):
so
2x(x+1) + 3(x+1) = ??
OpenStudy (anonymous):
(2x+3)(x+1)
hartnn (hartnn):
\(\huge \checkmark\)
now put that in numerator
hartnn (hartnn):
can u see anything cancelling ?
OpenStudy (anonymous):
yes (2x+3) would remain after cancelling, you would substitute next to get 1 as your answer
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OpenStudy (anonymous):
thanks :D
hartnn (hartnn):
welcome ^_^