How do you find the equation given A(-2, 1) and B(3, 7)?

1 Answer
Jun 29, 2017

See a solution process below:

Explanation:

First, we must 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)(7) - color(blue)(1))/(color(red)(3) - color(blue)(-2)) = (color(red)(7) - color(blue)(1))/(color(red)(3) + color(blue)(2)) = 6/5

We can now use the point-slope formula to find 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 first point in the problem gives:

(y - color(red)(1)) = color(blue)(6/5)(x - color(red)(-2))

(y - color(red)(1)) = color(blue)(6/5)(x + color(red)(2))

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

(y - color(red)(7)) = color(blue)(6/5)(x - color(red)(3))

We can now solve this equation for y to put the 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(red)(7) = (color(blue)(6/5) xx x) - (color(blue)(6/5) xx color(red)(3))

y - color(red)(7) = 6/5x - 18/5

y - color(red)(7) + 7 = 6/5x - 18/5 + 7

y - 0= 6/5x - 18/5 + (7 xx 5/5)

y = 6/5x - 18/5 + 35/5

y = color(red)(6/5)x + color(blue)(17/5)