Mathematics
8 Online
OpenStudy (dls):
Limits again :|
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OpenStudy (dls):
WAIT
OpenStudy (anonymous):
...
OpenStudy (dls):
\[\lim_{x \rightarrow 0}\frac{{\sqrt{1+2x^2}}-{\sqrt{1+x}}}{\sqrt{4+4x^2}-\sqrt{4-3x}}\]
hartnn (hartnn):
did u try multiply by conjugates ?
OpenStudy (dls):
yes but denominator is too big and messy
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OpenStudy (anonymous):
trying it...
hartnn (hartnn):
u get 4x^2 +3x in denom.
and 2x^2 - x in numerator
OpenStudy (dls):
i got just the numerator,denominator is scary to solve!
OpenStudy (anonymous):
seems to work
OpenStudy (dls):
how did u solve the den?
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OpenStudy (anonymous):
-2/3?
checking...
OpenStudy (dls):
yes correct
OpenStudy (anonymous):
multiply by the conjugates
OpenStudy (dls):
denominator..how to solve >.>
OpenStudy (dls):
seperate conjugates?
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OpenStudy (anonymous):
denom is (4x-3){ sqrt(1+2x^2) +sqrt(1+x) }
OpenStudy (dls):
yes
OpenStudy (anonymous):
lim (4x-3){ sqrt(1+2x^2) +sqrt(1+x) } = -6
x->0
OpenStudy (dls):
I have
(root of 4+4x^2 - root of 4-3x) (root o f 1+2x^2 + root of 1+x)
OpenStudy (anonymous):
naw multiply by the conjugates of both numerator and denom.
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OpenStudy (dls):
??
OpenStudy (anonymous):
so multiply that by sqrt(4+4x^2) +sqrt(4-3x) (also multiply it in the numerator though :P)
OpenStudy (dls):
okay o.O
OpenStudy (dls):
what am i made to do!!
OpenStudy (anonymous):
(4x^2 -3x)*(root o f 1+2x^2 + root of 1+x)
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OpenStudy (anonymous):
=x*(4x -3)*(root o f 1+2x^2 + root of 1+x)
OpenStudy (anonymous):
x is a factor in numerator as well...
OpenStudy (dls):
can't follow..
OpenStudy (anonymous):
ok?
OpenStudy (dls):
use drawing/equation
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OpenStudy (anonymous):
{ sqrt(4+4x^2) +sqrt(4-3x) }{ sqrt(1+2x^2) +sqrt(1+x) }
------------------------------------------------------
{ sqrt(4+4x^2) +sqrt(4-3x) }{ sqrt(1+2x^2) +sqrt(1+x) }
OpenStudy (anonymous):
ok?
OpenStudy (dls):
yes I did this
OpenStudy (anonymous):
great, then your numerator is
( 2x^2-x)(sqrt(4+4x^2) +sqrt(4-3x) }
OpenStudy (dls):
yes it is!
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OpenStudy (anonymous):
denom is
(4x^2-3x){ sqrt(1+2x^2) +sqrt(1+x) }
OpenStudy (anonymous):
factor out an x in both
OpenStudy (dls):
yes it is
OpenStudy (dls):
okay
OpenStudy (anonymous):
x( 2x-1)(sqrt(4+4x^2) +sqrt(4-3x) }
x(4x-3){ sqrt(1+2x^2) +sqrt(1+x) }
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OpenStudy (dls):
yes!
OpenStudy (anonymous):
ok?
OpenStudy (anonymous):
that's it, hole is gone. subs in x=0
OpenStudy (anonymous):
( 2x-1)(sqrt(4+4x^2) +sqrt(4-3x) }
-----------------------------------
(4x-3){ sqrt(1+2x^2) +sqrt(1+x) }
OpenStudy (dls):
yesyes!
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OpenStudy (dls):
imhere only
isit done?
OpenStudy (anonymous):
subs in x=0
OpenStudy (dls):
numerator turns out 0
OpenStudy (anonymous):
no.
OpenStudy (dls):
2(0)-1(0)
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OpenStudy (dls):
wait what its +
okay
OpenStudy (dls):
-1/3?
OpenStudy (dls):
isnt the denom 6?
3(2):?
OpenStudy (anonymous):
numerator is -4 denom is 6
OpenStudy (anonymous):
I have sign wrong:
should be:
( 2x-1)(sqrt(4+4x^2) +sqrt(4-3x) }
-----------------------------------
(4x+3){ sqrt(1+2x^2) +sqrt(1+x) }