Substitution

Take OUT the variable and PUT in the new expression y = 4x + 1 2x – y = 9 y = -2x -3 y = 6x + 1 y = 4x + 1 2x – y = 9 y = -2x - 3 y = 6x +1 2x – (4x + 1) = 9 -2x – 3 = 6x + 1

Take OUT the variable and PUT in the new expression y = 4x + 1 2x – 2y = 9 x = -2x -3 y = 6x + 1 y = 4x + 1 2x – 2y = 9 x= -2x - 3 y= 6x +1 2x – 2(4x + 1) = 9 y = 6(-2x – 3) + 1

Write the NEW equation after you substitute. Your Turn! Write the NEW equation after you substitute.

y = 6x – 11 -2x – 3y = -7 -2x – 3(6x-11) = -7

2x – 3y =-1 y = x - 1 2x – 3(x-1) = -1

y = -3x +5 5x – 4y = -3 5x – 4(-3x + 5) = -3

(-5x-17) = -x – 1 or (-x – 1) = -5x - 17 y = -x -1 Y = -5x - 17 (-5x-17) = -x – 1 or (-x – 1) = -5x - 17

y = -2 4x – 3y = 18 4x – 3(-2) = 18

x= -2y +11 -7x – 2y = -13 -7(-2y + 11) – 2y = -13

y = -5x – 21 y = 4x +6 (-5x - 21) = 4x + 6 or (4x + 6) = -5x - 21

y = 1/2x – 2 -5x + y = -2 -5x + (1/2x-2) = -2

x = -3y + 1 -3x – 3y = -15 -3(-3y + 1) – 3y = -15