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Mathematics 19 Online
OpenStudy (dtan5457):

More complex fractions. How should I solve this one?

OpenStudy (dtan5457):

\[\frac{ \frac{ 1 }{ z-7 } +\frac{ 7 }{ z }}{ \frac{ 1 }{ z^2-7z } -1}\]

OpenStudy (dtan5457):

it was a pain to write that...

OpenStudy (danjs):

multiply through by z(z-7)

OpenStudy (danjs):

the common denominator of the 4 fractions

OpenStudy (dtan5457):

so multiply by z just by the top part of the fraction?

OpenStudy (danjs):

\[[\frac{ 1 }{ z-7 } + \frac{ 7 }{ z }] * [z(z-7)]\]

OpenStudy (danjs):

that is the numerator

OpenStudy (dtan5457):

so \[\frac{ 1 }{ z^2-7z }+\frac{ 7 }{ z^2}\]

OpenStudy (dtan5457):

for the numerator

OpenStudy (danjs):

it would come to z + 7(z-7)

OpenStudy (dtan5457):

for what z^2-7z?

OpenStudy (danjs):

that is what the numerator simplifies to, you are going to multiply numerator and denominator by z(z-7)

OpenStudy (danjs):

\[[\frac{ 1 }{ z(z-7) } - 1]* [z(z-7)]\]

OpenStudy (danjs):

denominator goes to that... 1 - z(z-7)

OpenStudy (anonymous):

@kmorgan

OpenStudy (danjs):

so overall this is what you have \[\frac{ z + 7(z-7) }{ 1 - z(z-7) }\]

OpenStudy (dtan5457):

let me read that over..

OpenStudy (danjs):

i can type it all in one line here...

OpenStudy (dtan5457):

ahh the denominator of the numerator's first term would be z + 7(z-7)

OpenStudy (danjs):

\[\frac{ \frac{ 1 }{ z-7 }+ \frac{ 7 }{ z } }{ \frac{ 1 }{ z(z-7) } - 1 }*\frac{ z(z-7) }{ z(z-7) }\]

OpenStudy (dtan5457):

pretty sure there is z on top of the denominator's first numerator not a 1

OpenStudy (danjs):

\[\frac{ z + 7(z-7) }{ 1 - z(z-7) }\]

OpenStudy (danjs):

then the bottom would be z - z(z-7) instead

OpenStudy (dtan5457):

on the numerator isn't the denominator z(z-7) not x-7

OpenStudy (danjs):

i dont see an x. then you can now just multiply everything out if you want

OpenStudy (dtan5457):

so if i didn't change a thing on this question and just multiplied it out, i would still get the same answer?

OpenStudy (danjs):

i don't understand, what are you changing?

OpenStudy (danjs):

\[\frac{ 8z - 49 }{-z^2 + 7z + 1 }\]

OpenStudy (dtan5457):

this is all i have on my paper right now \[\frac{ \frac{ 1 }{ z(z-7) }+\frac{ 7 }{ z^2 } }{ \frac{ z }{ z(z-7) } -1}\]

OpenStudy (dtan5457):

i got lost from there

OpenStudy (danjs):

the common denominator of the 4 sub fractions is, \[z^2*[z(z-7)]\]

OpenStudy (danjs):

you can multiply that whole thing by \[\frac{ z^2[z(z-7)] }{ z^2[z(z-7)] }\]

OpenStudy (danjs):

So using distributive rule, multiply each fraction by z^2(z(z-7))

OpenStudy (danjs):

\[\frac{ z^2 + 7*z(z-7) }{ z*z^2 - z^2[z(z-7)] }\]

OpenStudy (danjs):

that gets rid of the fractions, now multiply all that out if you want

OpenStudy (triciaal):

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