Graph Question (1 Viewer)

sasquatch

Member
Joined
Aug 15, 2005
Messages
384
Gender
Male
HSC
2006
Im working from Fitzpatrick for graphs doing 30c.. For this set of exercises, it asks to find solutions to inequalities using graphs as aids. I have no problem doing that, but what ive noticed is for questions such as:

cos2x > (1/4), 0 <= x <= 2pi

The solution is written as:

0 <= x < pi/3 or 2pi/3 < x < 4pi/3 or 5pi < x <= 2pi

Why is it that at the begging and end parts of the graph bits, erm (0 <= x and the x <= 2pi parts), it is less than or equal... instead of just less than. And why does this only occur when the solution corresponds to parts of the domain given?

Wait.. i just realised that was a stupid question, its because AT zero, and 2 pi, those two points satisfy the inequality....nevermind anybody!
 
Last edited:

Riviet

.
Joined
Oct 11, 2005
Messages
5,593
Gender
Undisclosed
HSC
N/A
Hehe that's right, just remember to look at the domain, and not the original inequality. ;)
 

sasquatch

Member
Joined
Aug 15, 2005
Messages
384
Gender
Male
HSC
2006
Ok for a different question the answer says:


0 < x < pi/2, execpt pi/4

or

pi < x < 3pi/2, except 5pi/4


I wrote:

0 < x < pi/4, pi/4 < x < pi/2, pi < x < 5pi/4 or 5pi/4 < x < 3pi/2

Thats the same right?
 
Last edited:

Riviet

.
Joined
Oct 11, 2005
Messages
5,593
Gender
Undisclosed
HSC
N/A
sasquatch said:
Ok for a different question the answer says:


0 < x < pi/2, execpt pi/4

or

pi < x < 3pi/2, except 5pi/4


I wrote:

0 < x < pi/4, pi/4 < x < pi/2, pi < x < 5pi/4 or 5pi/4 < x < 3pi/2

Thats the same right?
Yep that's basically the same thing.
 

sasquatch

Member
Joined
Aug 15, 2005
Messages
384
Gender
Male
HSC
2006
What do you mean write 0? And um... im just gonna write it the way ive done hehe...
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top