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# Solved. :-) watch

1. Solved.
2. yep y=-2x is the equation for l2 so now you need to equate l1 to l2 so 3(-2x) -x + 21 = 0 then find x, sub that value back into either equation to get your y coordinate
3. (Original post by chemkid)
yep y=-2x is the equation for l2 so now you need to equate l1 to l2 so 3(-2x) -x + 21 = 0 then find x, sub that value back into either equation to get your y coordinate
Thank you.
4. (Original post by PoliticallyDiverse)
This is probably extremely simple, but I'm not sure if I know what's missing.

I have this question:

To which I have (for (a)):

Then for (b), I think it's y=-2x, but I'm not entirely sure as to the logic behind it; I'd essentially like to know why.

Thank you for any assistance.
If you think about it from the general equation of a line which you know:

What do you know here? Well, as it passes through the origin.

So what are you left with?

(Equally, just consider that a line can be expressed as : m is -2, as stated, and c will be 0 as that's the y-intercept (0, as crosses at the origin)).
5. (Original post by EEngWillow)
If you think about it from the general equation of a line which you know:

What do you know here? Well, as it passes through the origin.

So what are you left with?

(Equally, just consider that a line can be expressed as : m is -2, as stated, and c will be 0 as that's the y-intercept (0, as crosses at the origin)).
Ah, brilliant. Thank you very much.

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