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Mathematics 19 Online
OpenStudy (anonymous):

another

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 \[\frac{ 2x ^{2}+6 }{(x+3)(x-3) ? }\]

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):

\[5x ^{2}-15+7x-21\]

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):

\[12x ^{2}-21\]

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)

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 ^_^

OpenStudy (anonymous):

im gonna post a few more thanks for your help

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