Finding the equation of lines
A bit confused on this:
1. Find the equation of the line between the points (9, -9) and (-5, -2).
m=y2-y1 -2 - -9 7 = -1
--------- (over) --------- ---- ----
x2-x1 -5 - -9 -14 2
y=-1/2x+b ... How would I find b, the y-intercept then?
2. Find the equation of the line with an x-intercept of -2 and a y-intercept of 7.
That's the points (-2, 0) and (0, 7), so m=y2-y1/x2-x1 again, or 7-0/0--2 = 7/2....which would be y=7/2x+b and the y-intercept is 7 so the final equation would be y=7/2x+7 ? just checking.
3. Find the equation of the line that has the same x-intercept as x-4y=3 and the same y-intercept as 2x-3y=9.
x-4y=3 rearranges to x=4y+3, and to find the x-int you would substitute 0 in right for y so x=4(0)+3 or x=4+3, or x=7... so the x-intercept is 7.
For the y-intercept, 2x-3y=9 you substitute 0 in for x, so 2(0)-3y=9 would be 0-3y=9 or just -3y=9... or y=-3.
I guess the equation so far would be y=mx-3... but I don't know how I would find the slope at this point to finish the equation.
4. Finally... (the most important question) If A(1,2), B(-2,5) and C(3, 4), find the equation of the line perpendicular to AB and through C.
I know the slope of the line perpendicular to something is the negative reciprocal... but I don't know what to do here.
If I found the slope of A and B, that would be 2-5/-2-1 or -3/-3 or 1 I guess, so then would the slope of the new line be -1/2? What impact does "through C" have? The equation so far if that's right of the new line would be y=-1/2x+b... b being the y-intercept again, but I don't know what to do from this point on.
Thanks for reading! My math skills aren't great... or even "good" for that matter (Giggle)