4th LA1 Solving Systems of Equations

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 of the variables.

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

• Make sure both equations can be solved.

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

• intersecting lines
• parallel lines
• skew lines
• intersecting lines

Tags

CCSS.8.EE.C.8A

Which equation describes one of the lines in the system if the solution is (4,-1)?

• $-2x+y=-9$

• $y=-2x-9$
  

• $y=\frac{1}{3}x-4$

• $-x+3y=-4$

Check all that are correct steps for solving by substitution:

y = -x - 5

4x - 8y = 4

• $4x-8\left(-x-5\right)=4$
  

• $12x+40=4$
  

• $4x-8x+40=4$
  

• $12x=-36$
  

Solve the following system using the substitution method.

-7x - 2y = -13

X = 2y + 11

• (5,6)

• (3,-4)

• (-4, 4)

• (-3, -4)

Check all the correct steps for solving by substitution:

3x + 2y = 16

7x + y = 19

• Solve the second equation for y

• $3x+2\left(7x-19\right)=16$
  

• $-11x+38=16$
  

• $x=2$
  

How many solutions will this system have? 

• No solution
• One Solution
• I Don't Know
• Infinitely Many Solutions

Tags

CCSS.8.EE.C.8A

When you graph the exact same equation twice,

• you will have no solution. 
• you will have one solution.
• you will have infinite solutions. 
• you will graph a giraffe. 

Tags

CCSS.8.EE.C.8A

Solve the system of equations by graphing.
y = -4x + 5
y =  3x - 16

• (-3, -25)
• (3,-7)
• (11, 17)
• (21, 47)

Tags

CCSS.8.EE.C.8B

Check all that are true for solving the system:

3x + 2y = 16

7x + y = 19

• Solve by substitution by solving the second equation for y

• Multiply the first equation by -7 and the second equation by 3 to eliminate the x's

• Multiply the second equation by -2 to eliminate the y's

• Multiply the first equation by -1 to eliminate the x's