Math Is Fun Forum

tommy_loco

Member

Registered: 2008-06-01

Posts: 1

solving equations with x as denominator

how do i solve the following equation?

(9/x) + (3/x-2)  = 18/ x(x-2)

do i move everything to one side and find common denominator, or do i cross multiply?

hope someone can help me

iamthepro

Member

Registered: 2008-06-01

Posts: 1

Re: solving equations with x as denominator

(9x-18+3x)/x(x-2) = 18/ x(x-2)
The base is now the same so u can cancel them off
(12x-18)= 18
x = 3

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: solving equations with x as denominator

Just be careful when cancelling the denominator like that. It doesn't matter here, but if you do it blindly then you might run into problems.

For example, if the question was (9/x) + (9/x-2)  = 18/ x(x-2), then your method would eventually tell you that 18x = 36, which means that x=2. But in the original question, making x=2 causes division by 0.

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

Dragonshade

Member

Registered: 2008-01-16

Posts: 147

Re: solving equations with x as denominator

In mathsy's case