1. Standard 9 Solve a system of two linear equations

2. x = 7 x + 2x = 14 Example One. Instructions: Use substitution. Solve for x 2x+ 4 = 18 -4 ÷2 = 18isx + 4

3. x = 7 x + 2x = 14 Example One. Instructions: Use substitution. Solve for x 2x+ 4 = 18 -4 ÷2 = 18y =x + 4 y y = x + 4 y = ( ) + 4 y = 11 (7,11) x = 77

4. x = 5 x + 2 3x = 15 Example Two. Instructions: Use substitution. Solve for x 3x+ 6 = 21 -6 ÷3 = 21isx + 3 x+ 2x + 6 = 21 (x + 3) a +3

5. 3x = 3 2x + 2 4x = 12 Example Three. Instructions: x + 4 4x+ 8 = 20 -8 ÷4 y = x + 4 y = ( ) + 4 y = 7 (3,7) yy= 20=x + 4y=( ) 2x+ 2x + 8 = 20 y - x = 4 +x

7. -12n 3 3n+n 9n+3n False Parallel lines

8. and -16 -4a 4 a+4 4a+16 True Infinite many solutions

11. Instructions: Use substitution to solve for x Classwork One + 3x = 6(1)is 2x + 1 + 5x = 2(2) is 3x - 14 + 3x = 11(2) is x + 3 + 3x = 18(4) is x + 2

12. Instructions: Find where the lines intersect. Classwork Two (x,y) y + 3x = 6(1,3)y = 2x + 1 y + 5x = 2(2,-8)y = 3x - 14 2y + 3x = 11(1,4)y = x + 3 3y + 3x = 18(2,4)y = x + 2

13. Instructions: Find where the lines intersect. Classwork Three (x,y) y + 2x = 9(2,5)y – 2x = 1 y + 4x = 7(3,-5)y + 3x = 4 2y + 3x = 14(2,4)y – x = 2 2y + 3x = 8(4,-2)y + x = 2

14. Find the value of n that makes the equation true If no value of n works show that If all values of n work show that

15. Standard 14 solve quadratic equations ax² + bx + c = 0