MPM1D – Exam Review Chapter 5: Slope 1. Direct variation Has the formula 𝑦 = 𝑚𝑥 (m is slope) The graph passes through (0,0) There is no fixed cost or starting value 2. Partial variation Has the formula 𝑦 = 𝑚𝑥 + 𝑏 (m is slope, b is y-intercept) Does not pass through (0,0) Has a fixed cost or starting value 3. Slope is the rate of change a.k.a. the steepness of a line. In an equation, slope is represented by m It can be calculated from a graph or a table of values by using: rise 𝑦2 − 𝑦1 𝑚= or 𝑚= run 𝑥2 − 𝑥1 In a word problem, the slope is always given as a comparison between two units. Look for units written as fractions or the words per, each, every, etc. E.g.: km/hr, dollars per shift, number of sales every day The slope of a horizontal line is 0. The slope of a vertical line is undefined. 4. Parallel lines have the same slope. Find the slope of a line parallel to 𝑦 = −3𝑥 + 4: 5. Perpendicular lines have negative reciprocal slopes. Find the slope of a line perpendicular to 𝑦 = −3𝑥 + 4: 2 Find the slope of a line perpendicular to 𝑦 = 3 𝑥 − 1: