Expert: Ahmed Salami - 1/7/2010

Question
I'm having trouble trying to find the x intercept for this problem

(-7,-1),(5,2)

Answer
Hi Dominique,
First, you need to find the equation of the line (assuming you mean to find the x-intercept of the line that the two points fall on).
The equation of this line is
(y - y1)/(x - x1) = (y2 - y1)/(x2 - x1)
(y - -1)/(x - -7) = (2 - -1)/(5 - -7)
(y + 1)/(x + 7) = (2 + 1)/(5 + 7)
(y + 1)/(x + 7) = 3/12
(y + 1)/(x + 7) = 1/4
y + 1 = (x + 7)/4
The x-intercept is the point when y = 0, i.e
0 + 1 = (x + 7)/4
1 = (x + 7)/4
x + 7 = 4
x = -3

Regards