g raphing e quations & e quations of l ines lesson 13.1 & 13.2
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GRAPHING EQUATIONS & EQUATIONS OF LINESLesson 13.1 & 13.2
STRATEGIES TO GRAPH A LINE
• Make a table.• Special lines• Vertical lines• Horizontal Lines
• Intercepts (x, 0) & (0, y)• Slope-intercept form
MAKE A TABLE & GRAPH 2X – 4Y = 10
x -1 0 1 2
y -3 -5/2 -2 -3/2
SPECIAL LINES:GRAPH Y = 4 & X = -2
y = 4 is a horizontal line where all the y values are 4.
x = -2 is a vertical line where all of the x values are -2.
INTERCEPTSFIND THE X- AND Y- INTERCEPTS FOR THE LINE 2X – 5Y = 10, THEN GRAPH.
X –intercept:What is x when y is zero?2x – 5(0) = 10x = 5 …. (5, 0)
Y-intercept:What is y when x is zero?2(0) – 5y = 10y = -2 … (0, -2)
USE SLOPE-INTERCEPT FORM TO GRAPH THE LINE Y = 2X - 5.
y = mx + b y & x are any point (x, y) that line on
the line. m is the slope b is the y-intercept (0, b)
In the equation y = 2x – 5, m = 2 b = (0, -5)
Graph the y-intercept Graph the slope Connect the dots.
VARIOUS FORMS OF LINEAR EQUATIONS
Slope-Intercept Form (y-form) y = mx + b
Point-Slope Form y – y1 = m(x – x1) m = slope and (x1, y1) is a
known point
Standard Form (General Form) Ax + By = C
THINGS NOT TO FORGET ABOUT LINEAR EQUATIONS
1. Parallel Lines have the SAME slope but different y-intercepts.
2. Perpendicular lines have slopes that are negative reciprocals.
3. Vertical lines have a slope that is undefined.4. Horizontal lines have a slope of zero.5. Midpoint between two points is found using
the formula: x1 + x2 , y1 + y2
2 2
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