Conditions for which inequalitys is true

1. Mar 18, 2009

transgalactic

A:
1-mt<w^2(m+t)

B:
-(1+mt)<(w^2 )t(m-t)

i have 4 cases
for each case they said that needs to be a condition for which this case would be true
1: m>t and mt<1
so they say that i have to demand
w^2>(1-mt)/(m+t) which is inequality A

2: m<t and mt<1
they say that i have to demand
inequalitys A and B

why ??

2. Mar 18, 2009

HallsofIvy

If m< t, m- t is negative, if m> t, m- t is positive, if mt< 1, 1-mt is positive and w^2 is always positive.

3. Mar 18, 2009

transgalactic

so why in case two they demand both ??
it seems like the left side is true always
it cannot be negative?

4. Mar 18, 2009

transgalactic

why in the 1st case we only pick only one innequality
??

5. Mar 18, 2009

transgalactic

even if i substitute what you say regarding the positive and negative
i get
positive>positive

so??

6. Mar 18, 2009

transgalactic

wwoowww thanks i understood that stuff
:)