Can someone show me how to do this problem?

thetomps

Junior Member
A rancher has 20 miles of fencing to fence a rectangular piece of grazing land along a straight river. If no fence is required along the river and the sides perpendicular to the river are x miles long, find a formula for the area A(x) of the rectangle in terms of x. From practical considerations, what is the domain of the function A?

Thanks.

stapel

Super Moderator
Staff member
Draw the paddock and the river. Label as directed for the lengths perpendicular to the river, and label the remaining side as, say, "w". Write an expression, in terms of these variables, for the total perimeter not formed by the river. Set this expression equal to the given length of fencing.

(Who measures fencing in miles, anyway?!?)

Solve this equation for w in terms of x. You now have a variable for the length and an expression, in terms of that variable, for the width. Use these to form the "area" formula, A(x).

Eliz.

rachael724

Junior Member
I have been doing problems like this too. Can someone do this as an example?

Staff member

Thank you.

Eliz.

rachael724

Junior Member
This is NOT my problem, I just wanted to see how to do it!

stapel

Super Moderator
Staff member
Check your text; it should contain at least one or two worked examples.

Meanwhile, please be aware that this is not a classroom, but a tutoring forum. The tutors would like to help the original poster learn how to do this specific exercise. I'm afraid your desires may not rank above his needs.

Eliz.

happy

Full Member
Sent via pm

You are one of the nicest tutors on here. Can you show me how to do this problem. There is no rush I just need help. If I post on the board I get crap. Thanks.

Kay

A rancher has 20 miles of fencing to fence a rectangular piece of grazing land along a straight river. If no fence is required along the river and the sides perpendicular to the river are x miles long, find a formula for the area A(x) of the rectangle in terms of x. From practical considerations, what is the domain of the function A?