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(x/(x-2))-1 > 0

Created 24th November 2013 @ 15:30

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jx53

How do I solve this? I’ve tried every possible way so far yet I get the wrong answer

TWEEKARN\

ez-sports.ru

whats the point

atmo

x>2

jx53

Quoted from atmo

x>2

yes, I know but how?
(x/(x-2))-1 > 0
Why can’t I just move the 1 to the right side?

jx53

Quoted from TWEEKARN\

whats the point

what do you think…

Bonkers

TCM
HFoF

x/x-2 – 1 > 0
x/x-2 – x-2/x-2 > 0
x-x+2/x-2 > 0
2/x-2 > 0
2*(x-2) > 0
2x – 4 > 0
2x > 4
x > 2


Last edited by Bonkers,

atmo

(x/(x-2)) – 1 > 0
x(x-2) – 1 (x-2)^2 > 0
x^2 – 2x – (x^2 -4x + 4) > 0
x^2 – 2x – x^2 + 4x – 4 > 0
2x – 4 > 0
x > 2

if you multiply the whole line it has to be with a positive number so that the inequality does not change sign, so you use the square of the denominator (x-2).

jx53

Quoted from Bonkers

x/x-2 – 1 > 0
x/x-2 – x-2/x-2 > 0
x-x+2/x-2 > 0
2/x-2 > 0
2*(x-2) > 0
2x – 4 > 0
2x > 4
x > 2

2/x-2
2*(x-2)
Lines 4,5 wtf

jx53

Quoted from atmo

(x/(x-2)) – 1 > 0
x(x-2) – 1 (x-2)^2 > 0
x^2 – 2x – (x^2 -4x + 4) > 0
x^2 – 2x – x^2 + 4x – 4 > 0
2x – 4 > 0
x > 2

thanks, why can’t I multiple by x-2 at the beginning though


Last edited by jx53,

Bonkers

TCM
HFoF

if a/b > 0 then a*b > 0

jx53

Quoted from Bonkers

if a/b > 0 then a*b > 0

so (a/b > 0) = (a*b > 0)?

Why can’t I then?
(X/(X-2))-1 > 0
x^2-2x-1 > 0

that gives wrong answer :I


Last edited by jx53,

Tuto

8-)

all i see is banana + 1 > 0

atmo

Quoted from jx53

Quoted from atmo

(x/(x-2)) – 1 > 0
x(x-2) – 1 (x-2)^2 > 0
x^2 – 2x – (x^2 -4x + 4) > 0
x^2 – 2x – x^2 + 4x – 4 > 0
2x – 4 > 0
x > 2

thanks, why can’t I multiple by x-2 at the beginning though

Because you don’t know what value x-2 has at this point. If x turned out to be 0.5, then x-2 would be a negative number so you would be multiplying your inequality be a negative which means you have to change the inequality sign from > to <. That's why you square it to ensure that you are multiplying by a positive.

jx53

Quoted from atmo

[…]

Because you don’t know what value x-2 has at this point. If x turned out to be 0.5, then x-2 would be a negative number so you would be multiplying your inequality be a negative which means you have to change the inequality sign from > to <. That's why you square it to ensure that you are multiplying by a positive.

That sounds somewhat smart. Thanks

TWEEKARN\

ez-sports.ru

Quoted from jx53

[…]

what do you think…

that youll never have use for this at all

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