# 4-2 Writing Linear Equations Given Two Points

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4-2 Writing Linear Equations Given Two Points
Goal: Write the equation of a line in slope-intercept form given 2 points on the line. Eligible Content: A / A / A / A / A / A / A

Steps: Find the slope using the slope formula:
Find the y-intercept using y = mx + b Write equation by plugging slope and y-intercept into y = mx + b.

Find the equation of the line that passes through the points (1,6) and (3, -4).
Slope: y-intercept: pick either point 6 = -5 ‧ 1 + b 6 = b = b Write equation: y = –5x + 11 If I pick the other point, I will get the same answer: -4 = -5 ‧ 3 + b -4 = b 11 = b

Examples Write the equation of the line that goes through each set of points. (-3, 1) and (5, 5) (2, 3) and (3, 0) (-4, -3) and (2, 9) y = ½ x + 2.5 y = – 3x + 9 y = 2x +5

The table of ordered pairs shows the coordinates of two points on the graph of a line. Which equation describes the line? A. y = –x + 4 B. y = x + 4 C. y = x – 4 D. y = –x – 4

Write the equation of the line that passes through the points (–2, –1) and (3, 14).
A. y = 3x + 4 B. y = 5x + 3 C. y = 3x – 5 D. y = 3x + 5

Practice Page 229 #5-8

Homework Page 229 #16-21

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