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- Thread starter chr1s
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- Jan 30, 2012

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Now, $2.5/r$ can be represented as \(\displaystyle \frac{5}{2r}\). The author probably wanted to arrive at an equation with integer coefficients after multiplication.

- Jan 30, 2018

- 344

The "2" is just because they want integer coefficients. If you just multiply both sides by r(r+ 8) you get 4r+ 2.5(r+ 8)= r(r+ 8). Multiplying by 2 gives 8r+ 5(r+ 8)= 2r(r+ 8).

Another way of looking at it is that [tex]2.5= \frac{5}{2}[/tex] so that original form can be written as [tex]4/(r+ 8)+ 5/2r+ 1[/tex]. Now the "common denominator" is 2r(r+ 8).

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