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Mathematics 8 Online
OpenStudy (jessicawade):

function help?

OpenStudy (jessicawade):

\[Find (\frac{ f }{ g }) (x) for the functions provided: f(x) = x^2 − 9, g(x) = 3 − x\]

OpenStudy (jessicawade):

@Michele_Laino

OpenStudy (michele_laino):

here we have to evaluate the subsequent ratio: \[\frac{{{x^2} - 9}}{{3 - x}}\]

OpenStudy (jessicawade):

ok

OpenStudy (jessicawade):

i got x+3

OpenStudy (michele_laino):

now, we have to keep in mind that we can write the subsequent identity: \[{x^2} - 9 = \left( {x - 3} \right)\left( {x + 3} \right)\] so substituting in our ratio, we get: \[\frac{{{x^2} - 9}}{{3 - x}} = \frac{{\left( {x - 3} \right)\left( {x + 3} \right)}}{{ - \left( {x - 3} \right)}}\] since we have: 3-x=-(x-3) Please simplify, what do you get?

OpenStudy (jessicawade):

either x+3 or -x-3

OpenStudy (jessicawade):

oops i think im wrong

OpenStudy (michele_laino):

you can cancel similar terms

OpenStudy (michele_laino):

hint: |dw:1431631030840:dw|

OpenStudy (jessicawade):

oh i totally see it now

OpenStudy (michele_laino):

so, what is the result?

OpenStudy (jessicawade):

-x-3?

OpenStudy (jessicawade):

oh duh its x+3 because the others cancel out

OpenStudy (michele_laino):

there is -1 at the denominator

OpenStudy (michele_laino):

hint: |dw:1431631360001:dw|

OpenStudy (michele_laino):

at the numerator I have simplified by (x-3), namely I have computed this ratio: \[\frac{{\left( {x - 3} \right)}}{{\left( {x - 3} \right)}} = 1\] whereas at the denominator I have simplified by (x-3) too, so I have computed this ratio: \[\frac{{\left( {x - 3} \right)}}{{ - \left( {x - 3} \right)}} = - 1\]

OpenStudy (jessicawade):

ok

OpenStudy (jessicawade):

i still got -x-3 xD

OpenStudy (michele_laino):

that's right! -x-3= - (x+3)

OpenStudy (jessicawade):

so its f/g (x)= -x-3?

OpenStudy (michele_laino):

yes!

OpenStudy (jessicawade):

Yay! thanks again. P.s I really want to visit Italy :)

OpenStudy (michele_laino):

thanks! :)

OpenStudy (michele_laino):

and I really want to visit The United States of America! :)

OpenStudy (jessicawade):

ive heard that the food over there is amazing xD and p.s the american food is kind of gross. lol

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