Substitution Expressions

Substitute y = 2x - 1

into 4x + y = 10

• 4(2x - 1) + y = 10

• 4x + (2x - 1) = 10

• (4x + 10) = 2x - 1

• y = 2(y + 10) - 1

Substitute y = 2x

into y - x = 9

• -x + 9 = 2x

• y = 2(x - 9)

• y - (2x) = 9

• (2x) - x = 9

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Substitute x = 8

into 3x = 2y

• 3(8) = 2y

• 3x = 2(8)

• 3x + 8 = 2y

• 3x(8) = 2y

Substitute x = y + 1

into x + y = 2

• x(y + 1) + y = 2

• (y + 1) + y = 2

• x + (y + 1) = 2

• y + 1 = x + y

Substitute x = y - 3

into 5x = 10

• 5x = y - 3

• 5xy - 3 = 10

• 5(y - 3) = 10

• y - 3 = 10

Substitute y = 3x

into x - y = 1

• (3x) = 1

• (3y) - y = 1

• (3x) - y = 1

• x - (3x) = 1

Substitute y = x + 7

into 5 = 6y

• 5 = 6(x + 7)

• (x + 7) = 5

• (x + 7) = 6y

• 6y = (y)