Finding the Slope of a Line

Dear Professor Cram:

Find the slope of the line described by the equation: y + x = -3(14 – x/3)

KG, US Navy

KG, thank you for this algebra question. This is a pretty straight-forward question, so here's how we tackle it:

The Slope-Intercept form of the equation of a line is y=mx+b, where m is the slope and b is the y-intercept. If we can put your equation into this format, then we should be able to find m.

  • Y + x = -3(14 – x/3)
  • Y + x = (-3)(14) – (-3)(x/3)
  • Y + x = -42 – (-3x)
  • Y + x = -42 + 3x
  • Y = 3x -x -42
  • Y = 2x – 42

Thus, the slope is 2 and the y-intercept is -42.

Good studying,

Professor Cram