Turn on thread page Beta
    • Thread Starter

    how do you know whether to factorise it, complete the square, use the quadratic formulae ect?

    (Original post by Bertybassett)
    how do you know whether to factorise it, complete the square, use the quadratic formulae ect?
    I would never complete the square unless the question tells me to.

    There is sometimes a clue in the question. If it says find the solution to 2dp then use the formula otherwise I always try factorising first.

    Quadratic formula always works and it's easy as you just plug in numbers. Sometimes it can be a little bit quicker to complete the square in my opinion if the quadratic doesn't factorise (doesn't factorise nicely - any quadratic WILL factorise) - quadratic equations such as x^2-4x+1=0.
    Generally I think you want to see if it factorises first as if it does the solutions jump straight out. If not then just use the formula or complete the square if it is quick to do so. This is of course if this question doesn't say specifically how to do it.

    If its a calculator paper just use formula to save time.
    In non-calc, try factorising the normal way into two brackets, if you cannot find any solutions within a minute, complete the square.
    If a question asks you to complete the square, complete the square.

University open days

  • Southampton Solent University
    All faculties Undergraduate
    Sun, 18 Nov '18
  • University of Bradford
    All faculties Undergraduate
    Wed, 21 Nov '18
  • Buckinghamshire New University
    All Faculties Postgraduate
    Wed, 21 Nov '18
Black Friday: Yay or Nay?
Useful resources

Study tools


Essay expert

Learn to write like a pro with our ultimate essay guide.

Thinking about uni already?

Thinking about uni already?

See where you can apply with our uni match tool

Student chat

Ask a question

Chat to other GCSE students and get your study questions answered.


Make study resources

Create all the resources you need to get the grades.


Create your own Study Plan

Organise all your homework and exams so you never miss another deadline.

Resources by subject

From flashcards to mind maps; there's everything you need for all of your GCSE subjects.


Find past papers

100s of GCSE past papers for all your subjects at your fingertips.

Help out other students

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