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# How do you which method to use to solve quadratics? watch

1. how do you know whether to factorise it, complete the square, use the quadratic formulae ect?
2. (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.
3. 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.
4. 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.

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Updated: January 9, 2017
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