How do you write an equation of a line given point (1,0) and (5,-1)?

1 Answer
Jun 6, 2017

See a solution process below:

Explanation:

First, we need to determine the slope of the line. The slope can be found by using the formula: m = (color(red)(y_2) - color(blue)(y_1))/(color(red)(x_2) - color(blue)(x_1))

Where m is the slope and (color(blue)(x_1, y_1)) and (color(red)(x_2, y_2)) are the two points on the line.

Substituting the values from the points in the problem gives:

m = (color(red)(-1) - color(blue)(0))/(color(red)(5) - color(blue)(1)) = -1/4

Next we can use the point-slope formula to write an equation for the line. The point-slope formula states: (y - color(red)(y_1)) = color(blue)(m)(x - color(red)(x_1))

Where color(blue)(m) is the slope and (color(red)(x_1, y_1)) is a point the line passes through. Substituting the slope we calculated and the values from the second point in the problem gives:

(y - color(red)(-1)) = color(blue)(-1/4)(x - color(red)(5))

(y + color(red)(1)) = color(blue)(-1/4)(x - color(red)(5))

We can also substitute the slope we calculated and the values from the first point in the problem giving:

(y - color(red)(0)) = color(blue)(-1/4)(x - color(red)(1))

We can solve this equation for y to write an equation in slope intercept form. The slope-intercept form of a linear equation is: y = color(red)(m)x + color(blue)(b)

Where color(red)(m) is the slope and color(blue)(b) is the y-intercept value.

y = (color(blue)(-1/4) xx x) + (color(blue)(-1/4) xx -color(red)(1))

y = color(red)(-1/4)x + color(blue)(1/4)