1. By: Jeffrey Bivin Lake Zurich High School jeff.bivin@lz95.org Last Updated: October 11, 2005

2. y = 3x + 5 2x + 4y = 34 2x + 4(3x + 5) = 34 2x + 12x + 20 = 34 14x + 20 = 34 14x = 14 x = 1 y = 3(1) + 5 y = 3 + 5 y = 8 Jeff Bivin -- LZHS

3. Decide which variable you want to eliminate. I think I’ll choose to eliminate the y variable. Jeff Bivin -- LZHS 3x – 5y = 14 2x + 4y = -20

4. 3x – 5y = 14 2x + 4y = -20 12x - 20y = 56 10x + 20y = -100 22x = -44 x = -2 3(-2) – 5y = 14 -6 - 5y = 14 -5y = 20 y = -4 Jeff Bivin -- LZHS

5. Decide which variable you want to eliminate. I think I’ll choose to eliminate the x variable. Jeff Bivin -- LZHS 2x + 7y = 48 3x + 5y = 28

6. 2x + 7y = 48 3x + 5y = 28 6x + 21y = 144 -6x - 10y = -56 11y = 88 y = 8 3x + 5(8) = 28 3x + 40 = 28 3x = -12 x = -4 Jeff Bivin -- LZHS

7. Decide which variable you want to eliminate. I think I’ll choose to eliminate the x variable. Jeff Bivin -- LZHS 4x + 3y = -19 6x + 5y = -32

8. 4x + 3y = -19 6x + 5y = -32 12x + 9y = -57 -12x - 10y = 64 -y = 7 y = -7 6x + 5(-7) = -32 6x - 35 = -32 6x = 3 Jeff Bivin -- LZHS

9. y = -2x - 6 6x + 3y = 11 6x + 3(-2x - 6) = 11 6x - 6x - 18 = 11 - 36 = 11 Jeff Bivin -- LZHS

10. x = 5y + 1 2x - 10y = 2 2(5y + 1) - 10y = 2 10y + 2 - 10y = 2 2 = 2 Jeff Bivin -- LZHS