Geometry 3.5 Big Idea: Write and Graph Equations of Lines
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Transcript of Geometry 3.5 Big Idea: Write and Graph Equations of Lines
Geometry 3.5Geometry 3.5
Big Idea: Write Big Idea: Write and Graph and Graph
Equations of Equations of LinesLines
Reminder: One Way to Write a Reminder: One Way to Write a Linear Equation is Linear Equation is
Slope-Intercept FormSlope-Intercept Form
y = mx + by = mx + b
m = slope m = slope
b= y-interceptb= y-intercept
y-intercepty-intercept: point where : point where line crosses (intercepts) line crosses (intercepts) the the
y-axis (x = 0)y-axis (x = 0)
x-interceptx-intercept: point where : point where line crosses the x-axis line crosses the x-axis (y=0)(y=0)
Example: Write the equation of the given line.
Example: Given a line passes through the points (5,3) and (2, -6), write the equation of the line.
Ex.1) Find the equation of the line ║ to the line y = 5x – 2 that passes through the point (-3, 1).
Ex.2) Find the equation of the line ┴ to the line y = 5x – 2 that passes through the same point (-3, 1).
Standard FormStandard Form: Another : Another way to write a linear way to write a linear equation:equation:
ax + by = cax + by = c
(a, b and c represent (a, b and c represent numbers)numbers)
Ex.) Rewrite the equation in standard form.
Ex: Write the equation in standard form.
Ex: Graph the equation.
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6 7 8 9 10x
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
1
2
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9
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y
Ex: Graph the equation.
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6 7 8 9 10x
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
1
2
3
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5
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9
10
y
Remember, Remember,
If If no no ‘‘xx ’’ in equation, it in equation, it’’s a s a horizontalhorizontal line.line.
If If no no ‘‘yy ’’ in equation, it in equation, it’’s a s a verticalvertical line.line.