How do you find the slope and slope intercept form for #x+y=-5#?

1 Answer
Apr 7, 2015

The linear equation x + y = -5 is in a nice "general" form sometimes referred to as Standard Form: Ax + By = C. You can find the slope by doing one of two different things:

  1. Solve for y = (put the equation into slope-intercept form) or
  2. Use a "formula"

If you actually solve the Standard Form itself for y = ...
Ax + By = C
(subtract Ax from both sides)

By = -Ax + C
(divide both sides by B)

#(By)/B= (-Ax+C)/B#

#y = (-Ax)/B+C/B# might recognize that #-A/B# is the multiplier on x, and thus, the slope equals that number!

So, the slope for your equation x + y = -5 would be #(-1)/1# = -1.

This is the same way that you would put your equation into slope-intercept form:
#x + y = -5# (subtract x from both sides)
#y = -x + -5#
which helps you to identify both the slope (-1) and the y-intercept (-5).