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Do you recognise the quadratic forumla?

13 April 2012

The other handy method if you don't recognise the quadratic formula is to try and factorise the equation . By factorize I mean split it into the form where when you multiply out the brackets you get the above equation. Let me konw if you need a hand moving on from this bit.

14 April 2012

it doesnt matter which way around so you then know that x+2=0 and x+5=0

25 April 2012

oh dear... those are terribly horrible looking ways, their is an easier way. Whe you see a problem that looks like that ask your self two questions. What two number times together to give you 10 and add together to give you 7? OK have you thought about it? teh answer is 5 and 2 so what you do is write your answer like this (x+2)(x+5) = 0

25 April 2012

doing this to both equations givex x=-2 and x=-5!!!

25 April 2012

I am using separate posts so you can see each step. ok so now i rearrange each equation so if i take x+2=0 then depending on how you have been taught you either take two away from both sides or move the +2 over to give you -2

25 April 2012

you take the number infront of x2 which is 1 and times it t othe last number which is 10

25 April 2012

what times together to give 10 and adds together to give 7 ? 5 and 2 ?
then do x2+5x+2x=10
then factorise which will end up as (x+2) and (x+5) and x will either equal -2 or -5

25 April 2012

right but wouldn't introduce the coefficient of X2 until a student is comfortable and has become proficient at factorizing, but hey thats me!

25 April 2012

the number infront of the the 'x2' is timesd by the single number at the end
then you need to find what times together to get that number and also add together to give you the number infront of the single 'x'
when you figured that out, you factorise the fiirst section putting some into brackets and some out side, you do the same with the second section
you will NEED to end up having two brackets with the same things inside it along with something else on the outside infront of it
whatever is in front the bracket is put into a seperate bracket
the answer will be the newly made bracket and one of the brackets that had a 'twin'
dividing etc will give you the value of x

25 April 2012

x2+7x+10=0 ? [5 and 2, times to give 10 and add to give 7]
[substitue]x2+5x+2x+10
[factorise] x(x+5)+2(x+5)
[create seperate brackets] (x+2)(x+5)
[find what x is for each] x=-2or-5

25 April 2012

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