Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    These questions keep giving me problems even though, I should have cracked them by now. So, could someone explain to me the method to working them out? :puppyeyes:

    "The length of a rectangle is 3cm greater than its width. The area of the rectangle is 40cm². Find the length and width of the rectangle."

    Thank you for any replies.
    Offline

    1
    ReputationRep:
    if the width is x, what's the length in terms of x?

    what's the formula for area?
    Offline

    2
    ReputationRep:
    Let length = x

    Does this help:

    length * width = area

    x(x-3)=40
    • Thread Starter
    Offline

    0
    ReputationRep:
    Why is it minus 3, shouldn't it be plus 3?
    I also don't understand why you multiply length by itself. :confused:
    Offline

    1
    ReputationRep:
    (Original post by 123mccann)
    Why is it minus 3, shouldn't it be plus 3?
    I also don't understand why you multiply length by itself. :confused:
    lenght = width + 3

    if length is x, then width + 3 = x so width = x - 3

    you multiply length by width to get area

    length = x

    width = x - 3

    area = x(x - 3)
    Offline

    0
    ReputationRep:
    (Original post by 123mccann)
    Why is it minus 3, shouldn't it be plus 3?
    I also don't understand why you multiply length by itself. :confused:
    It depends what you make x equal.

    If x is width, length is (x + 3) as it is 3cm longer than width.

    However, if you want x to be the length, the width is (x - 3), as the width is 3cm shorter than length.

    The area of rectangle is length x width. So you now have an expression for both length and width. Just multiply out x(x + 3) = 40; or x(x - 3) = 40.


    The x in the first sum is the width, the x in the second sum is the length.
    • Thread Starter
    Offline

    0
    ReputationRep:
    Oh right, thank you very much. I understand it now. I just find it difficult putting the question into an equation. :confused:
    I'm pretty sure it will baffle me again next time. :p:
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: November 9, 2008

1,488

students online now

800,000+

Exam discussions

Find your exam discussion here

Poll
Should universities take a stronger line on drugs?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.