Find the Area of a rectangle please help

Question

a pool 20 ft by 30 ft is going to have a deck x feet wide added all the way around the pool write an expression in simplified form for the area of the deck. I have tried doing this but have failed please help

You said you have tried this? Specifically what have you tried? — Christopher K, Dec 13 '13 at 06:19
I tried (20+x)(30+x) I don't know is it right do I foil next? — crisrex, Dec 13 '13 at 06:22
Almost. But when you sketch the deck around the pool, it will be on all four sides. So it will increase the width/length by how much? — Christopher K, Dec 13 '13 at 06:25
The deck is on all four sides of the pool. Try drawing a picture. — Steve ODonnell, Dec 13 '13 at 06:26
@cis draw a rectangle in a rectangle. The outer rectangle will be the deck and the inner will be the pool. — yiyi, Dec 13 '13 at 06:33
@yiyi, I think we need to remove the four squares from the four corners if we draw a rectangle in a rectangle. — Vikram, Dec 13 '13 at 06:37

score 2 · Accepted Answer · answered Dec 13 '13 at 06:30

2

You are on the correct path cris.

The pool is still a rectangle, even with the new deck. Thus you are almost correct.

Each side will have $x$ feet added to it.

Thus it will be $(20+2x)(30+2x) = 4x^2+100x+600$

Try finding the answer to this:

If there is only 120 Feet of bamboo for the new deck,what is the largest the new area (pool + deck) can be.

answered Dec 13 '13 at 06:30

yiyi

7,352

thank you really helped it's 2x because there are 4 side right so 2+2 +4 so basically 2x is acounting for two sides right? – crisrex Dec 13 '13 at 06:34
There are only four side to a rectangle. Did you draw the rectangle in a rectangle? It always helps to draw a picture when you want to do mathematical problems. – yiyi Dec 13 '13 at 06:36
I did so is 4x squared + 100x + 600 right what is the point of drawing a rectangle wouldn't it be easier to just foil straight away? – crisrex Dec 13 '13 at 06:38
Cris, it so you can understand what is going on. Can you see where the deck would be on the outside of the pool. – yiyi Dec 13 '13 at 06:40
yeah so its like a picture frame the frame is the x and the picture is the length and width – crisrex Dec 13 '13 at 06:44
You also need to subtract the area of the pool. – Steve ODonnell Dec 13 '13 at 07:00

score 2 · Answer 2 · answered Dec 13 '13 at 07:04

2

enter image description here

Area of the deck=$20x+20x+30x+30x=100x$

answered Dec 13 '13 at 07:04

Vikram

5,580

is this the right answer or the one yiyi gave me? – crisrex Dec 13 '13 at 07:10
this one is right, read your problem and see the diagram above, then use the formula for the area of a rectangle. – Vikram Dec 13 '13 at 07:12
@cris Vikram did a better job of answering the problem than I did. You should accept his answer. – yiyi Dec 13 '13 at 07:12
i'm confused vikram gave me the answer but I only need the expression so wouldn't yours be right yiyi? – crisrex Dec 13 '13 at 07:14
the expression you want (you don't need) is Area of the deck=$2(20x)+2(30x)$, simplify this and you will get $100*x$ – Vikram Dec 13 '13 at 07:16
added all the way around the pool - been thinking about that phrase and I think that the corners should not be deleted. – yiyi Dec 13 '13 at 07:18
I agree @yiyi , if I hired someone to build a deck around my pool, I would expect the four corners to be included, so I could walk around the pool. – Steve ODonnell Dec 13 '13 at 07:28
1

in that case add $4x^2$, so the area of the deck=$4x^2+100x$ – Vikram Dec 13 '13 at 07:30
@Vikram how did you make the picture? – yiyi Dec 14 '13 at 03:24
@yiyi, MS Paint that comes with Windows. – Vikram Dec 14 '13 at 06:20

Find the Area of a rectangle please help

2 Answers2