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Maths help... algebra

(6 Posts)
CinnamonPretzel Sat 20-Aug-11 16:21:16

Quick question for any maths bods: -

= 5/2 + (-2)
= 5/2 - 2
= 5/2 - 4/2
= 1/2

why has it gone from 2 into 4/2?

Help appreciated.. and yes I should speak to my tutor but trying to catch up blush

winnybella Sat 20-Aug-11 16:24:58

because you need a common denominator for 5/2 and 2- so 2 is 2/1 multiplied by 2 so becomes 4/2. Now you can do 5/2 (which is 2.5) - 4/2 (which is 2) and you get 1/2 i.e. 0.5.

poppyknot Sat 20-Aug-11 16:25:16

So you can do the subtraction I think.

In addition and subtraction of fractions the denominator has to be the same in both numbers....

(Vague mists of time maths memory looming up from the depths)

spanieleyes Sat 20-Aug-11 16:31:55

You could, of course, have changed the 5/2 into 2 and a 1/2 and then subtracted the 2 from the 2 leaving just the 1/2!

CinnamonPretzel Sat 20-Aug-11 16:36:04

Thats very helpful. It brings back the hazey memory from some previous units on fractions etc. I didn't want to just move on in the questions without understanding why - so thank you for helping smile

CinnamonPretzel Sat 20-Aug-11 16:40:49

Yes Spaniel, that would have been my working - I've never been any good at fractions but slowly getting there. Strange how as an adult I'm picking up things easier - or maybe its just that they explain things in a way you can understand without making you feel small and stupid now smile

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