Straight-Line Graphs have the form $y=mx+c$ ($m$ = gradient, $c$ = y-intercept). Many curved relationships can be turned into a straight line to find constants.
For $y=3x-1$, when $x=2$, $y=5$. Parallel lines have equal gradients.
Remember
- $y=mx+c$.
- Convert to linear form $Y=mX+c$ to find constants.