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Graph Equations of Lines. Section 3.1 MATH 116-460 Mr. Keltner. When you are asked to relate to values in a real-world application, keep the units of the values in mind when describing a rate (miles, inches, degrees, pounds, dollars, etc.). Relating to real-world examples. Standard Form.
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Graph Equations of Lines Section 3.1 MATH 116-460 Mr. Keltner
When you are asked to relate to values in a real-world application, keep the units of the values in mind when describing a rate (miles, inches, degrees, pounds, dollars, etc.). Relating to real-world examples
Standard Form • A linear equation is in standard form when it is in the form Ax+By=C and A and Bare not both zero. • We can graph an equation in standard form by identifying and plotting the x- and y-intercepts. • Remember: • A y-intercept is the point where x=0. • An x-intercept is the point where y=0.
Graphing from Standard Form • Example 1 • Graph -2x -3y =6. • Start by finding the x- and y-intercepts, then connect those two points with a straight line. • This is the same line as
Steps to Graphing • To graph a linear equation in two variables: • Replace one of the variables with any number you choose (0 and 1 are easy to evaluate with). • Solve the equation for the other variable. • Repeat with at least two points. • It may help to construct a table of values.
y 5 x -5 -5 5 Example 2 • Graph 2x + y = 4.
HOY Horizontal lines are in the form y=c. Same y-value everywhere on the line. VEX Vertical lines are in the form x=c. Same x-value everywhere on the line. HOY VEX
Example 3 • Graph the lines -3 + x = 0 and 4y = 16. • Which line above belongs to which equation? • HOY VEX • The Horizontal line belongs to the equation with only a y in it. • The vertical line belongs to the equation with only an x in it.
Example 4: Finding Intercepts • Find the x- and y-intercepts for each equation below. Express your answers as ordered pairs. • x - y = -1 • 4x + 17y = 884
Assessment Pgs. 144-145: #’s 10-75, multiples of 5