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When there are two or more solutions, do you use OR or AND? (1 Viewer)

sinophile

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E.g solve (x-2)(x+4)=0

Would you say

The answers are 2 AND -4

or

The answers are 2 OR -4

:spzz:
 

MC Squidge

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"or", or "," but i dont think it matters if u use and
 

dp624

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some people can get really anal when you use AND
e.g
sinx=1
x= blah AND blah

that's wrong
 

axlenatore

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dont use or, that infers that only one of them is an answer, its best just to use at ","

ie (x+2)(x+1) = 0

x = -2,-1

or sin x = 0.5 for 0<x<pi

x = pi/6, 5pi/6
 

jet

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I say or. My maths teacher was really really anal when he was telling me this as an aside.
(x - 2)(x + 4) = 0
x = 2 OR x = -4
 

Trebla

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Use your common sense, if you say x = a AND x = b, you are sort of implying that they simultaneously hold, which is impossible.
e.g.
(x + 1)(x - 2) = 0
x = - 1 OR x = 2 (because the x can take EITHER one (not both) of -1 or 2)

It's not technically correct to say x = - 1 AND x = 2 because you're kind of saying x = - 1 and x = 2 at the same time, i.e. - 1 = 2 which is clearly false.

The use of AND/OR here is analogous to its use in probability. When events X AND Y occur, they occur together. When events X OR Y occur, it is either one of event X or event Y only (never both together).
 
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Drongoski

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Use your common sense, if you say x = a AND x = b, you are sort of implying that they simultaneously hold, which is impossible.
e.g.
(x + 1)(x - 2) = 0
x = - 1 OR x = 2 (because the x can take EITHER one (not both) of -1 or 2)

It's not technically correct to say x = - 1 AND x = 2 because you're kind of saying x = - 1 and x = 2 at the same time, i.e. - 1 = 2 which is clearly false.

The use of AND/OR here is analogous to its use in probability. When events X AND Y occur, they occur together. When events X OR Y occur, it is either one of event X or event Y only (never both together).
Trebla

I think this is not strictly correct. When A x B = 0, this can be as a result of only A = 0, only B=0 or both A= 0 and B=0. So the 'OR' should be the inclusive OR. So it can be both.
 

dp624

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But there are two variables in this case.
Perhaps using AND/OR would be pretty good xD
 

annabackwards

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But there are two variables in this case.
Perhaps using AND/OR would be pretty good xD
LOL.

I just use "or". I haven't had any problems with using that either... never seen anyone use "and" though.
 

Trebla

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Trebla

I think this is not strictly correct. When A x B = 0, this can be as a result of only A = 0, only B=0 or both A= 0 and B=0. So the 'OR' should be the inclusive OR. So it can be both.
Well that's a general example when A and B are both zero. But what I'm saying is that in solving the quadratic equation both factors cannot be zero at the same time.
e.g. (x + 1)(x - 2) = 0
There is no way that x + 1 = 0 and x - 2 = 0 together for the same value of x.
 

Drongoski

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Well that's a general example when A and B are both zero. But what I'm saying is that in solving the quadratic equation both factors cannot be zero at the same time.
e.g. (x + 1)(x - 2) = 0
There is no way that x + 1 = 0 and x - 2 = 0 together for the same value of x.
You've got a point.
 

AnandDNA

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just use ',' to be on the safe side and not need to run this detailed debate through your head during exams
 

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