Homework Help: Algebra

Posted by Celina on Tuesday, December 16, 2008 at 4:38pm.

Another question:

A cell phone company charges $60 for a cell phone and $40 per month under its economy plan. Formulate and graph a model that can be used to determine the total cost, C(t), of operating a cell phone for t months. Find the total cost for 5 and 1/2 months of service and the domain of C.

I understand everything except how you would find the domain of C. Please walk me through it so I can apply it to other problems. Thank you so much!

Algebra - Reiny, Tuesday, December 16, 2008 at 5:33pm
did you have C(t) = 40t + 60 ?

now the graph would only make physical sense for the part in the first quadrant.

the y-intercept is the point (0,60), (even with no calls you would pay $60)

the graph would continue to rise as t increases.
so the lowest Cost is 60 and there is really no upper limit, but we have to be reasonable about large values of t
e.g. if t = 1000, this would make no sense because 1000 months from now, cells phones may only be found in museums.

I would say the domain of t is any reasonable value of t , t > 0

you said "domain of C", what you meant is the range of C

domain deals with the horizontal variable,
range deals with the vertical variable of your function.
Algebra - Celina, Tuesday, December 16, 2008 at 7:23pm
That's funny, because in my packet, it said to "find the domain of C." But I see how that would not make sense.

Thanks!

Answer this Question

Related Questions

Gr10 Math - Charlene is looking into cell phone plans. Cell plus gives unlimited...
ALGEBRA HELP OR I AM GONNA FAIL I CANT DO THIS - compare two cell phone ...
Algebra - ABC phone company charges $18 per month plus 7 cents per minute of ...
Algebra - ABC phone company charges $16 per month plus 8¢ per minute of ...
Algebra - ABC phone company charges $16 per month plus 8¢ per minute of ...
Statistics - Professor does not teach from a book so am not sure how to apply ...
Algebra - Use the five steps for problem sovling. Company A charges $25 per ...
Statistics - I have a take home test I am working on. Any help would be ...
math - 73. Cell Phone Plan A cell phone plan costs $3.95 per month plus $0.07 ...
algebra - Marissa has budgeted $65 for her monthly cell phone expense. If her ...

For Further Reading

First Name:
School Subject:
Answer: