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Mathematics 9 Online
OpenStudy (anonymous):

solve this limit:

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.....

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 ??

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

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)

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

OpenStudy (anonymous):

thanks :D

hartnn (hartnn):

welcome ^_^

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