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OpenStudy (anonymous):
\[\frac{ 5x }{ x ^{2}-9 }+\frac{ 7 }{ x+3 }\]
OpenStudy (anonymous):
Make common denominator of x^2 -9
OpenStudy (anonymous):
ok so it shoud be \[\left( x+3 \right)\left( x-3 \right)\]
hartnn (hartnn):
yeah, thats x^2-9
now what will you do to make the denominator of 7 also
(x+3)(x-3) ?
OpenStudy (anonymous):
well i got for the whole thing \[\frac{ 2x ^{2}+6 }{(x+3)(x-3) ? }\]
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hartnn (hartnn):
lets check :
\(\large \frac{ 5x }{ x ^{2}-9 }+\frac{ 7 }{ x+3 }\times \frac{x-3}{x-3}=\frac{5x+7(x-3)}{(x+3)(x-3)}\)
i don't think that will simplify to what u have written...
OpenStudy (anonymous):
or is it 12x
hartnn (hartnn):
whats 5x+7(x-3) = ?
OpenStudy (anonymous):
ya it was 12xi got not 2x
OpenStudy (anonymous):
\[5x ^{2}-15+7x-21\]
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hartnn (hartnn):
why do u have 5x^2-15 ??
u don't need to multiply 5x with x-3
hartnn (hartnn):
as the denom. already is (x+3)(x-3)
so the numerator stays as 5x only
OpenStudy (anonymous):
oh ok so 5x+7x-21
hartnn (hartnn):
yeah, which is?
OpenStudy (anonymous):
\[12x ^{2}-21\]
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hartnn (hartnn):
5x+7x=(5+7)x =?
OpenStudy (anonymous):
(x+3)(x-3)
OpenStudy (anonymous):
12x
hartnn (hartnn):
yes, so numerator will be?
OpenStudy (anonymous):
(x+3)(x-3)
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hartnn (hartnn):
that is denominator
OpenStudy (anonymous):
yes so my awnser shoujld be \[\frac{ 12x-21 }{ (x+3)(x-3) }\]
hartnn (hartnn):
that is absolutely correct.
if u want you can factor out 3 from numerator
OpenStudy (anonymous):
ok thank you. soooo much
hartnn (hartnn):
welcome ^_^
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