7.3 Linear Equations and Their Graphs Objective: To graph linear equations using the x and y intercepts To graph horizontal and vertical lines

Linear Equations (Graphs are straight lines) 1.Equation is linear only if the each variable has an exponent of “1”. 2.(exponent in denominator is not linear) 3.Products of variables not linear, ie (x)(y) y = 2x + 1y = x y – 3x = -7 5y = 14 xy = 2

y - intercept x - intercept y X

Graphing using Intercepts 1)Let x=0 and determine the y-intercept. 2)Let y=0 and determine the x-intercept 3)Plot both points. Connect them with a line.

Graph 4x + 3y = 12 using intercepts Find x-intercept 4x + 3(0) = 12 Find y-intercept 4(0) + 3y = 12 4x = 12 x = 3 3y = 12 y = 4

Graph 2x + 3y = 12 using intercepts xy 0 0 6

Graph 3x + 5y = 15 using intercepts xy 0 0 5

Graph 5x - 2y = 10 using intercepts xy 0 0 2

Graph 2y = 3x - 6 using intercepts xy 0 0 2

Horizontal and Vertical Lines The graph of y= # is HORIZONTAL The graph x =# is VERTICAL

Graph 4y = 16 using 3-points xy 0 3 6

Graph 3x = 18 using 3-points xy

Differences between graphing by using a table and graphing by finding the x and y intercepts When graphing by a table you need to solve for y (Slope Intercept Form y=mx+b) When graphing by finding the x and y intercepts you do not have to solve for y (Standard Form Ax +By =C)

Assignment Page – 40 (even) (use graph paper)