Year 12s: what will be the first way you research your future options? >>

Maximum and minimum problem

Electrogeek

Hello everyone.

I need some guidence on how to do part a for this question. Can you help?

Reply 1

C00kie99

The quality is terrible post a better pic man

Reply 2

Kevin De Bruyne

If you could rotate the image that would be helpful :colondollar:

Reply 3

Electrogeek

Hope that this one is better quality, and it is the right way round. :-)

(edited 8 years ago)

Reply 4

Alexion

Original post by Electrogeek

Hope that this one is better quality, and it is the right way round. :-)

ya first post was upside-down, and the second is an invalid attachment...

Upload it to http://imgur.com/ and then wrap it in tags to guarantee it'll work :h:

Reply 5

Electrogeek

http://imgur.com/6ewpWW2

Here's a link to the photo with the problem. I only need help with part a. :-)

Reply 6

Indeterminate

Original post by Electrogeek

Hello everyone.

I need some guidence on how to do part a for this question. Can you help?

Well, what does the fact that she used 72 square metres of wood say about the surface area of the bookcase? Once you've written that down, use those dimensions to find an expression for V, and then use both pieces of information to eliminate d and get the required result :smile:

(edited 8 years ago)

Reply 7

Electrogeek

Original post by Indeterminate

Well, what does the fact that she used 72 square metres of wood say about the surface area of the bookcase? Now use those dimensions to find an expression for V, and that will enable you to eliminate d and get the required result :smile:

So do you mean that x times d times x/2 will give it, or do I have to use the net to make 72?

Reply 8

Indeterminate

Original post by Electrogeek

So do you mean that x times d times x/2 will give it, or do I have to use the net to make 72?

You have to write down 2 things, the first of which you already know about (the volume).

The second thing to write down is the surface area, which you know is 72.

Both of these things involve d, but you can use the information about the surface area in order to make d the subject and get V in terms of x only :smile:

Reply 9

Electrogeek