Download Solving Linear Systems using the Elimination Method

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7.3+7.4 - Solving Linear Systems using the
Elimination/Combination Method
 Line up the two equations in Standard Form.
 Choose either the x’s or y’s to cancel – you want the ___________________
(the number out front) to be equal but ______________ sign. If this doesn’t
match yet, _____________ one/both equations by a number so that the
coefficients do match.
 Add the equations together – watch one variable disappear.
 Solve and substitute back in the first equation to solve for the other variable
 Express your answer as an ordered pair (____, ____)
Example #1:
Example #2:
Example #3:
Try these:
1.
3.
4.
5.
2.
Homework 7.3+7.4: Solve each system by Linear Combination.
1. –4x – 2y = -12
4x + 8y = -24
2. x – y = 11
2x + y = 19
3. –2x – 9y = -25
-4x – 9y = -23
4. y + 8x = -16
-3x + y = -5
5. –4x + 9y = 9
x – 3y = -6
6. –3x + 7y = -16
-9x + 5y = 16
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7. –x – 7y = 14
-4x – 14y = 28
9.
x  2y  7
3x  2 y  5
11.
3c  6d  6
5c  2d  14
8. 4x + 15y = 17
-10x – 20y = -25
10.
12.
6 x  y  14
10 x  y  2
3x  5 y  10
5 x  7 y  10