How do you write the point slope form of the equation given (1,9) and (-2,-2)?

1 Answer
Apr 11, 2017

See the entire solution process below:

Explanation:

First, we must determine the slope. 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)(-2) - color(blue)(9))/(color(red)(-2) - color(blue)(1)) = (-11)/(-3) = 11/3#

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.

We can now substitute the slope we calculated and the values from the first point giving:

#(y - color(red)(9)) = color(blue)(11/3)(x - color(red)(1))#

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

#(y - color(red)(-2)) = color(blue)(11/3)(x - color(red)(-2))#

#(y + color(red)(2)) = color(blue)(11/3)(x + color(red)(2))#