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 ??