How to draw inequalities on a graph?
Maths and statistics discussion, revision, exam and homework help.
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Re: How to draw inequalities on a graph?You draw the line , solid line if <= or >= and a dotted line if just < or >, then you shade the area you don't want, a quick way to check which area to shade is to choose a point on one side of the line and put the values into the inequality, if it comes out false you shade that side of the line, if true you shade the other side...(Original post by blueray)
Can someone explain how to draw these on a graph? And what they would look like?
Thanks.
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Re: How to draw inequalities on a graph?Basically, change the inequality signs to equal signs and then you have your equations for lines.(Original post by blueray)
Can someone explain how to draw these on a graph? And what they would look like?
Thanks.
Then you can either re-arrange them for y=... and plot the graph accordingly by subbing in x values.
Or the simpler and supposedly quicker route is to for all of these lines find the point where x is 0 and then the point where why is 0 and join them up to get your line. Do this for all the lines and you are sorted. -
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Re: How to draw inequalities on a graph?You don't need to do dotted or solid lines. Look at the markscheme; they are all solid lines.(Original post by iCiaran)
You draw the line , solid line if <= or >= and a dotted line if just < or >, then you shade the area you don't want, a quick way to check which area to shade is to choose a point on one side of the line and put the values into the inequality, if it comes out false you shade that side of the line, if true you shade the other side... -
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Re: How to draw inequalities on a graph?(Original post by GreenLantern1)
You don't need to do dotted or solid lines. Look at the markscheme; they are all solid lines.
Only because they are all "or equal to" -
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Re: How to draw inequalities on a graph?(Original post by iCiaran)
You draw the line , solid line if <= or >= and a dotted line if just < or >, then you shade the area you don't want, a quick way to check which area to shade is to choose a point on one side of the line and put the values into the inequality, if it comes out false you shade that side of the line, if true you shade the other side...
(Original post by GreenLantern1)
You don't need to do dotted or solid lines. Look at the markscheme; they are all solid lines.
Ok cheers guys, rearranged it and have got y= .....etc etc(Original post by TenOfThem)
Only because they are all "or equal to"
Now I will plot them
But what was the rule? My teacher told me that it depends on certain factors. I forgot what they are ( did that in year 9) Can you explain them fully?
I have bolded that part above, can anyone verify it?
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Re: How to draw inequalities on a graph?Mate I am doing this exam. I have also seen in other markschemes that where it is just > or < it has been produced with solid lines.(Original post by TenOfThem)
Only because they are all "or equal to" -
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Re: How to draw inequalities on a graph?Well considering the OP didn't mention which exam/exam board, it's quite impressive you know which one they are doing...(Original post by GreenLantern1)
Mate I am doing this exam. I have also seen in other markschemes that where it is just > or < it has been produced with solid lines.
Dotted lines for < or > and solid for <= or >= is just convention, the mark scheme may allow only using solid lines, but using dotted is the "proper" way to do it. -
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Re: How to draw inequalities on a graph?Well, mate, I do not know which syllabus the OP is following, nor which one you are following(Original post by GreenLantern1)
Mate I am doing this exam. I have also seen in other markschemes that where it is just > or < it has been produced with solid lines.
I do know that there are exam boards that have dumbed down the requirements for mathematical accuracy because it seems that expecting students to follow conventions is too much .... and you may be correct that this is an example of that
However ... I think it is better to give explanations that include all the mathematically correct information whenever possible
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Re: How to draw inequalities on a graph?(Original post by iCiaran)
Well considering the OP didn't mention which exam/exam board, it's quite impressive you know which one they are doing...
Dotted lines for < or > and solid for <= or >= is just convention, the mark scheme may allow only using solid lines, but using dotted is the "proper" way to do it.
It is not actually impressive that I know which qualification and exam board the OP is doing, since we are both members of the Current Year 11 thread and he frequently PMs me questions about this Add Maths exam, of which he did to this link. Just saying.(Original post by TenOfThem)
Well, mate, I do not know which syllabus the OP is following, nor which one you are following
I do know that there are exam boards that have dumbed down the requirements for mathematical accuracy because it seems that expecting students to follow conventions is too much .... and you may be correct that this is an example of that
However ... I think it is better to give explanations that include all the mathematically correct information whenever possible
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Re: How to draw inequalities on a graph?Fair enuf but this s for a specific exam so I feel it would make more sense for him to just do what is required for the exam.(Original post by TenOfThem)
Well, mate, I do not know which syllabus the OP is following, nor which one you are following
I do know that there are exam boards that have dumbed down the requirements for mathematical accuracy because it seems that expecting students to follow conventions is too much .... and you may be correct that this is an example of that
However ... I think it is better to give explanations that include all the mathematically correct information whenever possible
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Re: How to draw inequalities on a graph?I am not saying that you do not know ... just that I don't and would rather give correct information(Original post by GreenLantern1)
It is not actually impressive that I know which qualification and exam board the OP is doing, since we are both members of the Current Year 11 thread and he frequently PMs me questions about this Add Maths exam, of which he did to this link. Just saying.
Surely, even if your board does not require it now, it is better to know the conventions in car you go beyond your current level.
Just saying -
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Re: How to draw inequalities on a graph?As I said in post 13(Original post by GreenLantern1)
Fair enuf but this s for a specific exam so I feel it would make more sense for him to just do what is required for the exam.
Current exam is often a stepping stone rather than the finish line -
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Re: How to draw inequalities on a graph?True, but I was only letting him now that for this exam he din't need to do that.(Original post by TenOfThem)
As I said in post 13
Current exam is often a stepping stone rather than the finish line
Btw the other post as more directed to the other person when I was saying it wasn't impressive. -
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Re: How to draw inequalities on a graph?then you shade the area you don't want, a quick way to check which area to shade is to choose a point on one side of the line and put the values into the inequality, if it comes out false you shade that side of the line, if true you shade the other side...
Is this correct? Does it always apply to everything.
(charlie, this is what I was talking about)
(Original post by GreenLantern1)
It is not actually impressive that I know which qualification and exam board the OP is doing, since we are both members of the Current Year 11 thread and he frequently PMs me questions about this Add Maths exam, of which he did to this link. Just saying.
We will both be doing the same exam, but Green they are right with the dotted thing, my maths teacher told me that as well.
Either way green is still great at maths
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Re: How to draw inequalities on a graph?(Original post by blueray)
then you shade the area you don't want, a quick way to check which area to shade is to choose a point on one side of the line and put the values into the inequality, if it comes out false you shade that side of the line, if true you shade the other side...
Is this correct? Does it always apply to everything.
Yes -
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Re: How to draw inequalities on a graph?Which qualification/exam board are you taking?(Original post by GreenLantern1)
Mate I am doing this exam. I have also seen in other markschemes that where it is just > or < it has been produced with solid lines. -
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Re: How to draw inequalities on a graph?The question says(Original post by TenOfThem)
Yes
shade the region which the region does not allow,
so I do that icirian says.
But if the question said
shade the region which the region does allow
then what would I do? -
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Re: How to draw inequalities on a graph?Well there are two regions so you would just shade in the other region (for each inequality).(Original post by blueray)
The question says
shade the region which the region does not allow,
so I do that icirian says.
But if the question said
shade the region which the region does allow
then what would I do?
I doubt that an exam question would ask you to shade in the "wanted" region.Last edited by notnek; 06-05-2012 at 16:02.
Thanks.
