 # Write and Graph Equations of Lines

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Write and Graph Equations of Lines
Section 3 – 5 Write and Graph Equations of Lines

Vocabulary Slope-intercept form: y = mx +b m = slope b = y-intercept

Vocabulary Standard Form: Ax + By = C
x-intercept: The x-coordinate of a point where a graph crosses the x-axis. y-intercept: The y-coordinate of a point where a graph crosses the y-axis.

Example 1 Write the equation of the line in slope-intercept form. m = 4 1 = 4 b = -3 x y = 4x – 3 y

Example 2 Step 1: What is the slope of the given line? 6
Write an equation of the line passing through the point (2, -3) that is parallel to the line y = 6x + 4. Step 1: What is the slope of the given line? 6 Step 2: Put the given point and the slope into slope-intercept form to solve for b. Step 3: Take the slope & y-intercept and write the new equation. y = mx + b -3 = 6(2) + b -3 = 12 + b y = 6x – 15 b = -15

Example 3 Step 1: What is the slope of the given line? -½
Write an equation of the line passing through the point (3, -4) that is perpendicular to the line y = -½x – 1. Step 1: What is the slope of the given line? Step 2: Find the opposite reciprocal: 2 Step 3: Put the given point and the new slope into slope-intercept form to solve for b. y = mx + b -4 = 2(3) + b Step 4: Take the slope & y-intercept and write the new equation. -4 = 6 + b b = -10 y = 2x – 10

Homework Section 3-5 Page 184 – 187 3 – 6, 9, 10 – 20 even,
22 – 24, 27, 29, 32, 33