Section 3: solving Systems of Equations with combinations/elimination
Review When is it easiest to solve a system of equations using the graphing method? When is it easiest to solve a system of equations using the substitution method?
Solve the System by Graphing y = 5x – 4 y = 2x - 1
Solve the System using Substitution x = 2y x + 5y = 6
Elimination/Combination Elimination/Combination is best used when both equations in the system are in standard form (Ax + By = C) This method combines both equations by adding or subtracting them together, but one of the variables must be eliminated as soon as the equations are combined.
Ex 1: Solve using Elimination/Combinations 4x – 2y = 7 x + 2y = 3 * are the equations in standard form?
Elimination/Combination – part 2 Review: Solve the system. 2x – 3y = 10 4x + 3y = 8
Example- Subtracting 4x+9y=1 4x+6y=-2
EX 2: Solve the System 2x – 3y = 6 -2x + 3y = -6 If 3x – 4y =12, can you write another equation to make the system no solutions?
Class Work Pg 126 # 18-23, 29
Ex 3: Solve the system using Elimination A. 4x + 9y = 2 B. -5x + 8y = 16 2x – 5y = 6 10x + 24y = 15
Ex 4: Solve using Elimination 3x + 7y = 15 5x + 2y = -4
HOMEWORK Eliminations Worksheet – 1 st column 2 nd column is bonus Eliminations Open Response #2