(2 A/B) Solving System of Equation by Substitution

Solve:

x = -3y - 17

2x + 3y = -7

• (1, -20)

• (10, 0)

• (-5, -2)

• (10 , -9)

3x + 2y = 8

-x + y = -11

• (-5,6)

• (6,-11)

• (-6,-5)

• (6,-5)

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:
y = 2x -11
-3y = -6x -15

• (-1.5,-4)
• (1.5,4)
• No solution (parallel lines)
• Infinitely many solutions

Which ordered pair is a solution to the system:

 $x=2y+5$  
 $2x-3y=7$  

• (-1, 3)

• (1, -3)

• (-1, -3)

• (3, 1)

^{What is the solution?} 

• 1
• -2
• (1, 2)
• (1, -1)

The solution (x, y) to a system of equations is the point where they...? 

• Run off the graph
• Don't touch
• Intersect
• Exist

If a system of equations has no solution, what does the graph look like? 

• intersecting lines
• parallel lines
• same lines

How many solutions will this system have?

• One
• Two
• No Solution
• Infinitely Many Solutions

Solve the system by substitution. 
-5x - 4y = -9
y = 6

• (3, 6)
• (6, -3)
• (-3, 6)
• (6.8, 3)