Thread: Domain and range

Hi.

Two questions.

1: f(m) = -2 / (-3+9m)

i got a domain (-infinity, 0.33) U (0.33, infinity) and range (-infinity, 0) U (0, inifinity). correct?

2: f(w) = 7 / ( -2 + |w| )

i have no idea about number two. help please~!

Domain can't include 2 or-2

How did you get that?

Originally Posted by tankertert

Hi.

Two questions.

1: f(m) = -2 / (-3+9m)

i got a domain (-infinity, 0.33) U (0.33, infinity) and range (-infinity, 0) U (0, inifinity). correct?

2: f(w) = 7 / ( -2 + |w| )

i have no idea about number two. help please~!

Hence :



Hence , domain is :

Really need help guys.

how do i find range for first question and second?

Originally Posted by tankertert

Hi.

Two questions.

1: f(m) = -2 / (-3+9m)

i got a domain (-infinity, 0.33) U (0.33, infinity)

Well, it would be far better to write "domain (-infinity, 1/3) U (1/3, infinity)". Do you see why?

and range (-infinity, 0) U (0, inifinity). correct?

One way to handle a "range" problem is to convert it into a "domain" problem by looking at the inverse function. The domain of is the range of f and vice-versa.

If we write them so and . Now what value can y not be?

2: f(w) = 7 / ( -2 + |w| )

Much the same. We cannot have -2+ |w|= 0 so we cannot have |w|= 2. What values of w are forbidden?
(This is the one biffboy was referring to.)

As for the range, again, let y= 7/(-2+ |w|) so that |w|- 2= 7/y so |w|= 2+ 7/y. What can y not be?

i have no idea about number two. help please~![/QUOTE]