Substitution Review

solve for x and y
x + y = 7
y = 4
Substitute y for 4 in the second equation
Subtract 4 from both sides
Your answer is (x,y)

• (3,4)

• (4,-1)

• No solution 

• Infinite solutions

If y=4,find the value of 3y+5

• 27

• 12

• 17

If y=10
find the value of 5(y+1)

• 11

• 55

• 20

If y=7,find the value of 2(y+4)

• 11

• 22

• 20

Solve for x and y (Use Substitution)

y = 2x + 1

y = 4x - 1

• (1,3)

• (-1,-3)

• (-1,3)

• (3,1)

• (1,1)

Solve the system of equations using substitution:

-4x + 4y = 8

y = -2x - 10

• (-4, -2)

• (12, -34)

• (4, -18)

• (-2, -6)

• (-4, 6)

What is the first step in solving a system by Substitution?

• Make sure both equations are in standard form.

• Make sure at least one equation is solved for one variable.

• Make sure both equations are in slope-intercept form.

• Make sure both equations can be solved.

Solve:
x = -3y - 17
2x + 3y = -7

• (1, -20)

• (3, 0)

• (-5, -2)

• (10 , -9)

• (1, 2)

• (4, 1)

• (2, -1)

• No Solution

Solve:
y = 7x + 7
2y + 2x = -18

• (5, 0)

• (9, 18)

• (-2, -7)

• (1, 16)