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#1 2006-04-12 22:35:49

dadon
Member
Registered: 2006-04-12
Posts: 14

Rational equation & Rearranging formula

i needed some help

how do you so the following rational equation

(x-1)^2 / x-2 = 9 / 2

and also

how do you make y the subject of the formula when

y+2 / y+1 = x

i been trying to solve this all morning!

anyways guys if you can help please

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#2 2006-04-12 23:14:50

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: Rational equation & Rearranging formula

(x-1)²/(x-2) = 9/2

Multiply by (x-2): (x-1)² = 9/2(x-2)

Expand the brackets: x² -2x +1 = 9/2x - 9

Rearrange into quadratic form: x² -13/2x +10 = 0

Solve: x = 2.5 or 4

---

(y+2)/(y+1) = x

Rewrite the numerator: (y+1+1)/(y+1) = x

Take out the common factor: 1 + 1/(y+1) = x

Get the y term on its own: 1/(y+1) = x-1

Multiply by y+1: 1 = (x-1)(y+1)

Get the y term on its own: 1/(x-1) = y+1

Make y the subject: y = 1/(x-1) -1


Why did the vector cross the road?
It wanted to be normal.

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#3 2006-04-12 23:20:30

dadon
Member
Registered: 2006-04-12
Posts: 14

Re: Rational equation & Rearranging formula

thank you exactly what i needed! smile

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#4 2006-04-12 23:59:46

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,555

Re: Rational equation & Rearranging formula

Bravo!


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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