8.1 Solving Systems of Linear Equations by Graphing EQ – HOW CAN YOU SOLVE A SYSTEM OF EQUATIONS BY GRAPHING?
A. Recall … SLOPE INTERCEPT FORM y = mx + b m = b =
B. Graphing Slope-Intercept Form 1. Graph the y-intercept (0,b) on the y-axis 2. Graph the slope (m) of the line using …. Rise/Run (If there’s whole number turn it into a fraction ALWAYS, ALWAYS, ALWAYS … Y/X
C. Vocab… System of equations – set of equations that have the same variables Solution of a system of equations – an ordered pair to show where the system of equations cross each other. (The point where they meet) The solution MUST work for both equations of the system
D. Rewriting to Slope-Intercept Form From ax + by = c: 1. subtract ax from both sides 2. divide both sides by b 3. Rearrange equation to fit => y = mx + b Example x – 3y = 2 -3x + 9 y = - 6 { x – 3y = 2 -x -3y = 2 – x Y = 1/3x - 2/3 -3x + 9y = x 9y = x y = 1/3x – 2/3
Solving Systems by Graphing Write the equation in slope-intercept form – GET Y BY ITSELF Graph each equation Find the point where the lines intersect Check: Plug the point into both equations to see if it works for both equations One solution
Pg. 228 … Example B Infinitely Many
Result# of SolutionsGraphWhat does it look like? x=a1Lines Cross a=aInfinite ManySame Line 0Lines don’t cross
Word Problems Standard Form ax + by = c Rewrite both of the equations in slope-intercept form