Write an Equation Given Two Points

Key Questions

  • What is the formula to find the slope given two points?

    Slope Formula

    The slope formula of the line passing through the points (x_1,y_1) and (x_2,y_2) can be found by:

    m={y_2-y_1}/{x_2-x_1}

    So to find the slope of a line segment joining the points ( 2, - 5) and (- 2, 4).

    First, label the points as x_1 = 2, y_1 = - 5, x_2 = -2 and y_2 = 4

    m={y_2-y_1}/{x_2-x_1} = {4- -5}/{-2- 2} = {9}/{-4} = {-9}/{4}

    So, the slope (m) = -9/4.

    Wataru · 3 · Nov 13 2014
  • Does it matter which point you use to solve for the y-intercept?

    No, it does not as long as the point is on the line. You will end up with the same value for the y-intercept.

    I hope that this was helpful.

    Wataru · 1 · Oct 31 2014
  • What is the equation in slope intercept form when the slope is undefined?

    If the slope of a line is undefined, then the line is a vertical line, so it cannot be written in slope-intercept form, but it can be written in the form: x=a, where a is a constant.

    Example

    If the line has an undefined slope and passes through the point (2,3), then the equation of the line is x=2.

    I hope that this was helpful.

    Wataru · 3 · Nov 3 2014
  • How do you write an equation in slope intercept form given two points?

    Answer:

    Use the differences in the y and x values to find the slope then substitute the values of one point into the equation to find b the y intercept.

    Explanation:

    Slope = ( y_1-y_2)/(x_1-x_2)=m

    By putting the x and y values for the two points into the slope equation the value for m can be found.

    The equation of a line in the slope intercept form is

    y = mx +b

    After finding m using the slope equation substitute one set of point values for y and x. This leaves b as the only unknown. Slope the resulting equation for b.

    David Drayer · 1 · May 29 2018

Questions

Forms of Linear Equations