Math Is Fun Forum
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#1 2014-03-05 13:53:49
What am I doing wrong? #Coordinate_Geometry
I am using this formula to do the problem.
Let (x,y) be a point in the line segment joining (x[sub]1[/sub],y[sub]1[/sub]) and (x[sub]2[/sub],y[sub]2[/sub]). If (x,y) divide the mentioned line segment in the ratio m:n, then:
The Problem is the following:
In what ratio does the line 2x + y - 4 = 0 divide the line segment joining (2,-2) and (3,7)?
Here is how I am doing it.
Let the point of intersection be (x,y)
Since it lies on the line
Let the ratio of division be m:n.
Then by the formula above, we are getting this:
Ok, now for the y coordinate:
Substituting y with 4-2x,
Combing the two equations,
Solving,
Thus,
But then the answer should be 2:9. What am I doing wrong?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#2 2014-03-05 15:25:22
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
Hi;
You are using the endpoints of the line segment that you were given to determine the ratio. Why are you not using the intersection point?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#3 2014-03-05 16:09:18
Re: What am I doing wrong? #Coordinate_Geometry
I am calling the intersection point (x, 4-2x). These co-ordinates can be found by the formula in the begining of the post.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#4 2014-03-05 16:20:12
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
You are correct with the intersection points. I trust that after all we have talked that you have done the calculations using M so that their is not a silly arithmetic or algebraic error?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#5 2014-03-05 16:26:55
Re: What am I doing wrong? #Coordinate_Geometry
No because I will not be allowed to use M 5 days from now, so I am preparing for it and improving my arithmetic.
I guess you did not check your last post for a grammar error?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#6 2014-03-05 16:32:39
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
Drills improve your arithmetic, problems improve your understanding. GrammarD? She died many years ago.
I will check your calculations and I will use M.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#7 2014-03-05 16:35:57
Re: What am I doing wrong? #Coordinate_Geometry
You may use M but please do not use any hi-fi commands. Only use it to do petty equation solving and polynomial solvings.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#8 2014-03-05 16:40:07
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
Hi-fi, you must be quite old to remember that.
How was that derived?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#9 2014-03-05 16:56:05
Re: What am I doing wrong? #Coordinate_Geometry
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#10 2014-03-05 17:04:40
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
Can you justify that?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#11 2014-03-05 17:09:45
Re: What am I doing wrong? #Coordinate_Geometry
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#12 2014-03-05 17:20:19
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
Substituting y with 4-2x,
Can you justify that?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#13 2014-03-05 17:29:03
Re: What am I doing wrong? #Coordinate_Geometry
After substitution,
So, that is the bug?
Last edited by Agnishom (2014-03-05 17:31:20)
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#14 2014-03-05 17:30:52
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
That is the first one found. Everything that comes after is of course wrong too. Please work out the rest of the answer.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#15 2014-03-05 17:31:51
Re: What am I doing wrong? #Coordinate_Geometry
Ok, please wait.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#16 2014-03-05 17:34:21
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
Then I will direct you to a famous story.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#17 2014-03-05 17:51:14
Re: What am I doing wrong? #Coordinate_Geometry
I got it!
Its 2:9 right?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#18 2014-03-05 17:58:18
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
Or 9:2. Yes, that is the answer I got so it has to be right.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#19 2014-03-05 18:15:11
Re: What am I doing wrong? #Coordinate_Geometry
Thats the answer that Geogebra gives too
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#20 2014-03-05 18:16:30
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
Geo, geo, he is the man. If he can not do it, nobody can. Yay geogebra!
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#21 2014-03-05 18:23:52
Re: What am I doing wrong? #Coordinate_Geometry
that is a negative thinking.
the next will tell a story
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#22 2014-03-05 18:27:57
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
That is positive thinking! People are not catching on to the amazing power that geo has. It combines, math, programming, hand and eye together. Wunderbar!
I already told that one.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#23 2014-08-09 15:42:38
Re: What am I doing wrong? #Coordinate_Geometry
n=var('n');
solve(66*8*n==2*binomial(n,2),[n])In a chess tournament, there are two women. Each player plays the other opponent twice. The number of times men play against each other is 66 times the men play against women. How many participants are there?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#24 2014-08-09 20:40:41
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: What am I doing wrong? #Coordinate_Geometry
n=var('n');
solve(66*8*n==2*binomial(n,2),[n])
The answer to that programming problem is n = 529. I did not check whether you set it up right or not.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#25 2014-08-09 20:57:18
Re: What am I doing wrong? #Coordinate_Geometry
I already ran that command and got 529 and 0. That is not what I was asking.
I need a solution to this:
There were two women participating in a chess tournament. Every participant played two games with the other participants. The number of games that men played between themselves proved to exceed by 66 the number of games that the men played with the women. How many men were there?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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