Expert: Ahmed Salami - 12/9/2008

Question
I am a 56 year woman re-entering college and I am having problems with these problems, please help me.
1. Passing through, (1,9 and 4,-2)

2. Passing through (7, 8) with x -intercept = 3

3.  Slope = -2/3, passing through (6,-4).


Answer
Hi Wanda,
1)(y - 9)/(x - 1) = (-2 - 9)/(4 - 1)
 (y - 9)/(x - 1) = -11/3
 3(y - 9) = -11(x - 1)
 3y - 27 = -11x + 11
 3y = -11x + 11 + 27
 3y = -11x + 38
 y = (-11/3)x + (38/3)

2)y = mx + c
at y = 0, x = 3
 0 = 3m + c
 c = -3m
at y = 8, x = 7
 8 = 7m + c
 8 = 7m - 3m
 8 = 4m
 m = 8/4 = 2
 c = -3m = -3(2) = -6
And so,
 y = 2x - 6

3)(y - -4)/(x - 6) = -2/3
  (y+4)/(x-6) = -2/3
   3(y+4) = -2(x-6)
    3y + 12 = -2x + 12
      3y = -2x
        y = (-2/3)x

Regards