Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    3
    ReputationRep:
    what does completing the square actually tell you?

    i know can be used to
    find the minimum point of a quadratic
    to derive the quadratic formula
    do c1 questions which require this skill

    what uses does it have?
    Offline

    15
    ReputationRep:
    Can be used to solve quadratics more conveniently.
    Manipulate expressions in integrands to make things easier to integrate.
    Offline

    1
    ReputationRep:
    (Original post by thefatone)
    what does completing the square actually tell you?

    i know can be used to
    find the minimum point of a quadratic
    to derive the quadratic formula
    do c1 questions which require this skill

    what uses does it have?
    Pretty much what you said. It's sort of an easier way to factorise a quadratic.
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by john_jomcy98)
    Pretty much what you said. It's sort of an easier way to factorise a quadratic.
    i know but it doesn't give the fully factorised version/using the forumla
    Offline

    18
    ReputationRep:
    It's used in FP3 to turn things in to a different form that is easier to integrate
    Offline

    22
    ReputationRep:
    (Original post by thefatone)
    Completing the square
    I know that this isn't the directly related to the question but you might enjoy reading this post.
    Offline

    2
    ReputationRep:
    (Original post by Zacken)
    I know that this isn't the directly related to the question but you might enjoy reading this post.
    can you have quadratics with imaginary numbers?
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by Student403)
    It's used in FP3 to turn things in to a different form that is easier to integrate
    (Original post by B_9710)
    Can be used to solve quadratics more conveniently.
    Manipulate expressions in integrands to make things easier to integrate.

    that's new.... da how i wish i did further maths now >.>

    (Original post by Zacken)
    I know that this isn't the directly related to the question but you might enjoy reading this post.
    will do...
    Offline

    22
    ReputationRep:
    (Original post by Youngmetro)
    can you have quadratics with imaginary numbers?
    Yes. Do you mean as coefficients or factoring them over the complex plane? If it's the former: definitely, if it's the latter: still definitely. The complex number field acts as the algebraic extension or closure of the real number field, so you can definitely factorise a quadratic with real coefficients into two linear factors.
    Offline

    11
    ReputationRep:
    (Original post by thefatone)
    what does completing the square actually tell you?

    i know can be used to
    find the minimum point of a quadratic
    to derive the quadratic formula
    do c1 questions which require this skill

    what uses does it have?
    You have asked two different questions here, but I'll give an answer to the first: completing the square tells you that, given a rectangle, you can always find a square with a smaller square removed, with the same area as the rectangle. For example:

    x^2+6x = x(x+6) is the area of a rectangle of sides x, x+6. But by competing the square, we have x(x+6) = (x+3)^2-3^2 which is the area of a square of side x+3 with a smaller square, area 3^2 removed.

    You can see a graphical representation of this here: http://www.thestudentroom.co.uk/show...79&postcount=5
    Offline

    22
    ReputationRep:
    (Original post by atsruser)
    You can see a graphical representation of this here:
    Perhaps more complicated than needs be, but meh:

    Offline

    11
    ReputationRep:
    (Original post by Zacken)
    Perhaps more complicated than needs be, but meh:

    That's neat, but not very easy to follow, I think.
    Offline

    22
    ReputationRep:
    (Original post by atsruser)
    That's neat, but not very easy to follow, I think.
    Yeah, I agree - I much preferred your simpler and more concise example.
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by atsruser)
    You have asked two different questions here, but I'll give an answer to the first: completing the square tells you that, given a rectangle, you can always find a square with a smaller square removed, with the same area as the rectangle. For example:

    x^2+6x = x(x+6) is the area of a rectangle of sides x, x+6. But by competing the square, we have x(x+6) = (x+3)^2-3^2 which is the area of a square of side x+3 with a smaller square, area 3^2 removed.

    You can see a graphical representation of this here: http://www.thestudentroom.co.uk/show...79&postcount=5
    (Original post by Zacken)
    Perhaps more complicated than needs be, but meh:

    thanks both of you, now i can understand why it's called completing the square xD
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?
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.