Thread: range of values

I can't remember how to find the range of values of a function to save my life!

e.g.
Given that 2x+3y-5=0, find the range of values of x if y<6.

Thanks in advance!

Originally Posted by colloquial

I can't remember how to find the range of values of a function to save my life!

e.g.
Given that 2x+3y-5=0, find the range of values of x if y<6.

Thanks in advance!

One way:


So


So you want to solve

for x.

-Dan

also the question:
Find the range of values of p if 3p^2 + 2p >= 5
so I did:
3p^2 + 2p - 5 >=0
(3p+5) (p-1)>=0
is that even correct?
:S

then I would have to draw the number line right?

thanks again!

Originally Posted by colloquial

also the question:
Find the range of values of p if 3p^2 + 2p >= 5
so I did:
3p^2 + 2p - 5 >=0
(3p+5) (p-1)>=0
is that even correct?
:S

then I would have to draw the number line right?

thanks again!

Here you need to be a bit more careful.







Now split the number line into 3 pieces:
(based on where the LHS is 0) and test your inequality on each of these intervals. The intervals that work give you your solution set.

In this case:
:

:

:

So your solution set will be
.
(I have included the end points because of the relation. If this had been a > you would not include these points.)

-Dan