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Alexis1994_13
(1+x)/(1-x)>0 What's next? :S
multiply both sides by the denominator
you cannot do that as 1-x can be negative, You can do that be wavy curve method, Or common sense, If a ratio has to be +ve, both numerator n denominator have to be of the same sign, 1+x >0 , x>-1 1-x >0 , x<1 common soln. (-1,1) 1+x<0 , x<-1 1-x<0 , x>1 common soln. (nothing!) Therefore, the ans is (-1,1)
if you multiply both sides by the denominator you would get 1 + x > 0(1 - x) which is 1 +x > 0
For some reason, I have to do this on paper, not in my head
you cannot multiply both sides by a variable in an inequality
@satellite: you can if you know that its gonna be +ve or -ve
I guess amogh it's right. Thanks guys.
your answer is all numbers between -1 and 1 i.e. (-1,1)
Satellite and amogh have the right idea.
I neglected to use critical points and the intervals between them
and it is easy enough to solve. for one thing you can just think of \[(1+x)(1-x)> 0\] which is a parabola facing down. therefore it is positive between the zeros and negative outside of them. the zeros are -1 and 1 so it is positive between those two numbers and negative outside of them
Very usefull site! Thank ya all :)
or you can say you have two factors , 1+x which is positive if x > -1 negative for x < -1 1-x which is positive if x < 1 and negative is x > 1 then what happens when you divide? if you are between -1 and 1 both are positive, and so the quotient will be as well