Don L. answered 01/05/17
Tutor
5
(18)
Fifteen years teaching and tutoring basic math skills and algebra
Hi Julia, to find the line passing through two points, start by finding the slope. The slope is given by the rise divided by the run, or the change in y values divided by the change in x values.
Let m represent the slope:
m = (y2 - y1) / (x2 - x1)
m = (4 - 0) / (-2 - 3)
m = 4 / -5
Next use the point-slope equation to find the line:
y - y1 = m * (x - x1)
It does not matter which of the two points is used to solve this equation.
Substitute for y1, x1, and m:
y - 4 = (4 / -5) * (x - (-2))
multiply by -5 to clear the fraction:
-5y + 20 = 4 * (x + 2)
-5y + 20 = 4x + 8
In standard form, the line is:
-4x - 5y = -12
Multiply by -1:
4x + 5y = 12
For the second part, to find the x- and y-intercepts, first set y = 0 and solve for x. Then set x = 0 and solve for y.
y = 0, 9x = 36, x = 4
x = 0, -2y = 36, y = -18
The x-intercept is 4, and the y-intercept is -18.
Questions?