#how would you guys solve it?

48 messages · Page 1 of 1 (latest)

loud glade
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how would you guys solve it and similar rational equations?

left quarry
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By decomposing the partial fractions.

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Multiply both sides by 3x+2 and 2x+1

loud glade
left quarry
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It depends on the rational equation. This one can decompose nicely

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You should actually multiply by

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(2x+1)(5x+4)

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Then 3x+2

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Any order doesn’t matter

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Just remove the denominators

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Get a fraction, say ax+b/(f(x))

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Then solve the top

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Check that f(solution) != 0

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Then you have finished

loud glade
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@left quarry can you do it on a paper and show me?

icy trench
left quarry
left quarry
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One method can solve all rational equations

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Literally called decomposing the fractions

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Let mw do it

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$\frac{4}{2x+1} + \frac{9}{3x+2}= \frac{25}{5x+4}$

carmine tangleBOT
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Lucifer

left quarry
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Next we will multiply by $(2x+1)(3x+2)$

carmine tangleBOT
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Lucifer

left quarry
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$(2x+1)(3x+2)\left(\frac{4}{2x+1} + \frac{9}{3x+2}\right)=(2x+1)(3x+2)\frac{25}{5x+4}$

carmine tangleBOT
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Lucifer

left quarry
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Reduce LHS

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$4(3x+2) + 9(2x+1)=(2x+1)(3x+2)\frac{25}{5x+4}$

carmine tangleBOT
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Lucifer

left quarry
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@loud glade this should be trivial to solve now

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Expanding the right hand side:

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$(2x+1)(3x+2)=6x^2+7x+2$

carmine tangleBOT
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Lucifer

left quarry
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$\frac{25(6x^2+7x+2)}{5x+4}$

carmine tangleBOT
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Lucifer

left quarry
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We can then simplify:

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There are two routes now

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Multiply both sides by 5x+4

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$(5x+4)(4(3x+2) + 9(2x+1))=25(6x^2+7x+2)$

carmine tangleBOT
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Lucifer

left quarry
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Then just expand this to get two quadratics:

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$150x^2 + 205x + 68$

carmine tangleBOT
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Lucifer

left quarry
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Then just solve this:

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$150x^2 + 205x + 68=25(6x^2+7x+2)$

carmine tangleBOT
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Lucifer