How do you find the equation through the line (3/4,-8) and (2,-5)?

1 Answer
Apr 16, 2017

See the entire 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))m=y2y1x2x1

Where mm is the slope and (color(blue)(x_1, y_1)x1,y1) and (color(red)(x_2, y_2)x2,y2) are the two points on the line.

Substituting the values from the points in the problem gives:

m = (color(red)(-5) - color(blue)(-8))/(color(red)(2) - color(blue)(3/4)) = (color(red)(-5) + color(blue)(8))/(color(red)(8/4) - color(blue)(3/4)) = 3/(5/4) = 12/5m=58234=5+88434=354=125

Now, 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))(yy1)=m(xx1)

Where color(blue)(m)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 second point gives:

(y - color(red)(-5)) = color(blue)(12/5)(x - color(red)(2))

(y + color(red)(5)) = color(blue)(12/5)(x - color(red)(2))

We can also substitute the slope we calculated and the first point giving:

(y - color(red)(-8)) = color(blue)(12/5)(x - color(red)(3/4))

(y + color(red)(8)) = color(blue)(12/5)(x - color(red)(3/4))

We can also solve the first 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)(5) = (color(blue)(12/5) xx x) - (color(blue)(12/5) xx color(red)(2))

y + color(red)(5) = 12/5x - 24/5

y + color(red)(5) - 5 = 12/5x - 24/5 - 5

y + 0 = 12/5x - 24/5 - 25/5

y = color(red)(12/5)x - color(blue)(49/5)