Optimisation

[Michelle16]

I am revising for Higher maths sqa assessment in May and have forgotten how to do this can someone help.
A farmer uses 60 metres of fencing to form a rectangular pen in a field:
a) given that the pen has breadth x cm find an expression for its area.
I worked out 60x - 2x^2 which is wrong but I dont know why.
b) find the greatest area that can be enclosed by the pen.
Cant work this out without correct answer to a)
Appreciate any help, Michelle

 

[Deleted member 4993]

I am revising for Higher maths sqa assessment in May and have forgotten how to do this can someone help.
A farmer uses 60 metres of fencing to form a rectangular pen in a field:
a) given that the pen has breadth x cm find an expression for its area.
I worked out 60x - 2x^2 which is wrong but I dont know why.
b) find the greatest area that can be enclosed by the pen.
Cant work this out without correct answer to a)
Appreciate any help, Michelle

You said you worked out:

60x - 2x^2 = ?

How did you formulate that expression?

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:

READ BEFORE POSTING

Please share your work/thoughts about this problem.

 

[HallsofIvy]

You know, I presume you know that "area= height*width". You know that the "width"= x cm (so x/100 metres) and the entire fencing is 60 metres. What does that leave for the "height"?