"Line crosses points M and N:

M(2;6), N(-2;-6), find the equation for it"

The only formula I found was

It works, but this is grade 9 (in our country) exercise, I think there should be a simpler way. Is there?

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- Feb 3rd 2011, 08:17 AMEvaldasFinding linear function.
"Line crosses points M and N:

M(2;6), N(-2;-6), find the equation for it"

The only formula I found was

It works, but this is grade 9 (in our country) exercise, I think there should be a simpler way. Is there? - Feb 3rd 2011, 08:34 AMAckbeet
In essence, any method you use is going to compute what you have there. The only equation for a line that I ever use is y = mx + b. For the case of two points on the line, I just plug both points into the y = mx + b equation to obtain two simultaneous equations. I solve that using any of the many valid methods, and then I'm done.

- Feb 3rd 2011, 08:35 AMskeeter
- Feb 3rd 2011, 08:48 AMguess
i guess you can just use observation for this problem. Notice that M is (2,6) and N is (-2,-6). Easily we can see that 6 is 3 times of 2 and -6 is also 3 times of negative two. Since it is a straight line, we can deduce that the line will be y=3x.