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Mathematics 22 Online
OpenStudy (anonymous):

solve for x!

OpenStudy (anonymous):

solve what

OpenStudy (anonymous):

\[\frac{ 1 }{ 2 } + \frac{ 4 }{ 2x }= \frac{ x+4 }{ 10}\]

OpenStudy (anonymous):

@Loser66 @amistre64 @myininaya

OpenStudy (amistre64):

id suggest multiplying the whole thing by 2x ... that should get rid of the fractions

OpenStudy (amistre64):

well, id still have a 5 underneath ... 10x it then

OpenStudy (anonymous):

what do you mean?

OpenStudy (anonymous):

how do i multiply fractions by 2x

OpenStudy (amistre64):

same way you multiply anything else by ... in this case lets make it 10x

OpenStudy (amistre64):

\[\frac{ 1(10x) }{ 2 } + \frac{ 4(10x) }{ 2x }= \frac{ 10x(x+4) }{ 10}\] and cancel what can be canceled i choose 10x so taht we would be able to work with integers

OpenStudy (anonymous):

oh ok i see

OpenStudy (anonymous):

i got \[\frac{ 10x }{ 2 } + \frac{ 40x }{ 2x } = \frac{ 10x^2 + 4 }{ 10 }\]

OpenStudy (amistre64):

while that is proper, it doesnt really use the notion of WHY we would multiply by 10x in the first place. \[\frac{ 1(10x) }{ 2 } + \frac{ 4(10x) }{ 2x }= \frac{ 10x(x+4) }{ 10}\] \[\frac{ 1(\cancel{10}^5x) }{ \cancel2 } + \frac{ 4(\cancel{10x}^5) }{ \cancel{2x} }= \frac{ \cancel{10}x(x+4) }{ \cancel{10}}\] \[5x+20=x(x+4)\]

OpenStudy (anonymous):

hmm i don't understand how that gets us x tho

OpenStudy (amistre64):

it just reworks it into a familar looking quadratic expression, and I assume you have been playing with quadratics?

OpenStudy (anonymous):

do i solve for x in the equation?

OpenStudy (amistre64):

\[5x+20=x(x+4)\] \[20=x(x+4)-5x\] \[20=x(x-1)\] just off hand, id say x is simple to SEE at this moment

OpenStudy (amistre64):

but yes, you would work it out so that you could solve for x, which may have 2 solutions \[5x+20=x(x+4)\] \[5x+20=x^2+4x\] \[0=x^2-x-20\]

OpenStudy (anonymous):

so x can equal -4 and 5 right

OpenStudy (anonymous):

@amistre64

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