contraposition (contrapositive) method

[MedAbs]

Soit a un réel strictement positif.
En utilisant le raisonnement par contraposée
Montrer que :

Mrc

 

[Deleted member 4993]

Soit a un réel strictement positif.
En utilisant le raisonnement par contraposée
Montrer que :
View attachment 25762
Mrc

It will help if you supply a english translation (along with picture of the original problem - which you did) because most of our tutors can understand english. That will facilitate prompt reply.

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:

READ BEFORE POSTING​

Please share your work/thoughts about this problem.

 

[MedAbs]

contraposition method for this:
For a>0

 

[Deleted member 4993]

contraposition method for this:
For a>0
View attachment 25772

What did you try?

Where are you stuck?

 

[MedAbs]

What did you try?

Where are you stuck?

I dont know how to prove it by contraposition.

 

[Deleted member 4993]

I dont know how to prove it by contraposition.

What is the definition of contraposition?

 

[MedAbs]

P --> Q
then contraposition is:
no Q -- > no P

 

[Deleted member 4993]

P --> Q
then contraposition is:
no Q -- > no P

So what would be the contrapositive statement for the given prposition in the problem.

 

[MedAbs]

The question is :
if a>0 prove that
a^6<5 --> a^5 - a^3 +1 < 3

with using contraposiyive method
a^5 - a^3 +1 >= 3 --> a^6>=5