Solving Systems by Substitution

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.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Why does substitution help us solve a system of equations?

• It changes one variable to an expression using the other variable, so we can solve an equation that only has one variable at a time.

• It creates a problem with fewer steps.

• It puts both equations in slope-intercept form for easy graphing.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

TRUE or FALSE:

When both equations have the same variable isolated

(both y = or both x = ),

substituting the first into the second ends up looking like

you just set the two equal to each other.

• TRUE

• FALSE

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

TRUE or FALSE:

If an equation is not set up to do what we need it to do,

or looks different than we want it to look,

WE CAN CHANGE IT

as long as we follow rules of equality when we do.

• TRUE

• FALSE

Tags

CCSS.HSA.REI.A.1

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

• intersecting lines
• parallel lines
• one horizontal and one vertical line

• intersecting lines

Tags

CCSS.8.EE.C.8A

If a system of equations has infinitely many solution, what does the graph look like? 

• intersecting lines
• parallel lines
• one horizontal and one vertical line

• coinciding lines (overlapping)

Tags

CCSS.8.EE.C.8A

If a system of equations has one and only one solution, what does the graph look like? 

• intersecting lines
• parallel lines
• one horizontal and one vertical line

• coinciding lines (overlapping)

Tags

CCSS.8.EE.C.8A

Which option shows the CORRECT substitution for this system?

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Which option shows the CORRECT substitution for this system?

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Which option shows the CORRECT substitution for this system?

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6