Equations from Intercepts — Cheat sheet

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Intercept form

xa+yb=1\dfrac{x}{a} + \dfrac{y}{b} = 1 - where aa is the xx-intercept and bb the yy-intercept.

Moves

SituationMove
Intercepts to equationsubstitute into intercept form, clear denominators
Equation to xx-interceptset y=0y = 0 and solve
Equation to yy-interceptset x=0x = 0 and solve
Slope from interceptsm=−bam = -\dfrac{b}{a}

When it does not apply

LineWhy
Through the originboth intercepts are 00, denominators vanish
Horizontal y=cy = cno xx-intercept
Vertical x=cx = cno yy-intercept