Easiest looking MATHS question is hard?

See photo.

Don’t you have to equate the sides given to 22cm and then rearrange to find x and y. Then substitute it back into the formula? I honestly don’t know if that will work but it’s worth a try 😂

Original post by frankabagnale

It's a rectangle, so opposite sides are the same.

This yields

2x+7y = x-2y

Secondly, considering the perimeter yields

(x-2y) + (2x+7y) + 16 = 22

These are two equations in two unknowns, so you can solve for x,y.

Reply 3

Pigster

20

Since it is a rectangle, x - 2y = 2x + 7y

Also, x - 2y + 2x + 7y = 22 - 2x8

Reply 4

Ryanthom100

22

Original post by frankabagnale

You again. The most useless person. You state the obvious and show no working to the actual answer. Also, i already knew this, as stated in the reply above. Give it a go (for once). It doesn't work.

NO ONE HELP HIM OUT, he sounds like a rude ****

Original post by frankabagnale

You again. The most useless person. You state the obvious and show no working to the actual answer. Also, i already knew this, as stated in the reply above. Give it a go (for once). It doesn't work.

So then do it correctly for once if you know how. It works just fine.

Original post by frankabagnale

I've tried, hence I'm asking in the student room?

Being rude to those who can help you is like shooting yourself in your foot. Bit stupid.

Good luck with the problem.

Reply 7

funky2722

10

Original post by frankabagnale

Doesn't work.

Neither does equating the two widths and finding x in terms of y or vise versa and then subbing that back in.

I'm clueless.

The two sides with x and y on them are equal since it's a regular rectangle with 2 pairs of equally lengthed sides. You also then add all 4 sides to get something equall to 22. Solve the 2 equations simultaenously.

Reply 8

thekidwhogames

18

Try what others said.

Reply 9

Theocrowley24

3

It's a rectangle so the opposite sides are equal. Therefore:

x - 2y = 2x + 7y

Rearrange for x:

x = -9y

Perimeter is 22. Therefore:

x - 2y + 16 + 2x + 7y = 22

Simplify

3x + 5y - 6 = 0

Substitute in x = -9y

-22y = 6
y = -3/11

Use this to find x, then sub x and y back into x - 2y or 2x + 7y to find the dimensions.

Dimensions are 3 by 8

(edited 6 years ago)

Reply 10

funky2722

10

Original post by frankabagnale

When i that y= (minus) 3/11

Even disregarding the minus, subbing that back in to find x, x comes to 27/11. It doesnt work when i test these in the original formula of the perimeter

that should be right, could you retry testing it? what are the actual answers?

Reply 11

username3249896

12

Original post by frankabagnale

When i that y= (minus) 3/11

Even disregarding the minus, subbing that back in to find x, x comes to 27/11. It doesnt work when i test these in the original formula of the perimeter

Those are correct.. Maybe try substituting into (x-2y) and (2x+7y) to find the sides?

Reply 12

Mehru1214

16

The people who made simultaneous equations were correct. Working on from that...

x = 27/11
y = -3/11

Let's find the length of the short side now.

x - 2y
= 27/11 - 2(-3/11)
= (27 + 6)/11
= 33/11
x = 3cm
y = 8cm

To check our solution, we calculate the perimeter.
3 + 3 + 8 + 8 = 22cm
I'm right!

Reply 13

Mehru1214

16

Original post by frankabagnale

Cheers pal, i was so confused all along because i disregarded the minus of -3/11 when i tried to find x. I guess i was thinking lengths can't be minus. My bad

THANKS ALL

No problem :smile:

Reply 14

Y2_UniMaths

19

Original post by frankabagnale

I've tried, hence I'm asking in the student room?

The Student Room is not a place to get people to do your homework for you. Be kind and respectful to people on here and in turn they will help you.

Reply 15

mupsman2312

11

Original post by frankabagnale

I've tried, hence I'm asking in the student room?

RDKGames is "the most useless person"? I think you meant one of the most helpful! I often seem to find myself repping them in various threads. In fact, so many times I've clicked on a thread to try to help someone, only to find that RDKGames has already done a brilliant job of it! As for actually "giving the question a go (for once)", they probably have, but simply gave advice on how to approach it - rather than just ignoring the TSR guidelines and posting a full solution.

If you're getting frustrated with the advice of RDKGames, then you must really just want to be spoon-fed the answer. Good luck with the exam (when you won't have anyone to tell you the answers).

If you're so adamant that a method doesn't work just because of something not seeming right at a point, then work it through to the final answer, and see if the answer is actually reasonable. Just because y is negative doesn't mean that the sides are negative too - they each also have an x-component to make them positive.

TL;DR: We're all more than happy to help you, but please don't be sarcastic with those trying to do so, or throw words like "useless" about at those who are legitimately helping.

Spoiler

Original post by mupsman2312

RDKGames is "the most useless person"? I think you meant one of the most helpful! I often seem to find myself repping them in various threads. In fact, so many times I've clicked on a thread to try to help someone, only to find that RDKGames has already done a brilliant job of it! As for actually "giving the question a go (for once)", they probably have, but simply gave advice on how to approach it - rather than just ignoring the TSR guidelines and posting a full solution.

If you're getting frustrated with the advice of RDKGames, then you must really just want to be spoon-fed the answer. Good luck with the exam (when you won't have anyone to tell you the answers).

If you're so adamant that a method doesn't work just because of something not seeming right at a point, then work it through to the final answer, and see if the answer is actually reasonable. Just because y is negative doesn't mean that the sides are negative too - they each also have an x-component to make them positive.

TL;DR: We're all more than happy to help you, but please don't be sarcastic with those trying to do so, or throw words like "useless" about at those who are legitimately helping.

Spoiler

Absolute fire right there :headfire: