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Cogito

Algebra 1 · Chapter 5 · Lesson 1

Practice Worksheet

Substitution and Elimination

Two ways to remove a variable.

10 problems · about 20 minutes · A-REI.C.6

NameDate

Figure — use these to answer the problems

The solution of a system is where the two lines cross.
-10-10-5-5551010
y = 2x + 1
Slope2
Intercept1
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

1 problem

  1. From “Intercepts and Standard Form”

    2x + 5y = 10. x-intercept?

    Answer

Warm Up

Straightforward practice. Get the method working first.

4 problems

  1. x + y = 15 and x − y = 3. What is x?

    Answer

  2. What do both methods achieve?

    • They remove one variable.
    • They draw the graph.

  3. x + y = 12 and x − y = 2. What is x?

    Answer

  4. y = 2x and x + y = 9. What is x?

    Answer

Build It Up

The same ideas with more to keep track of.

2 problems

  1. 3x + y = 11 and y = x + 3. What is x?

    Answer

  2. 2x + y = 7 and 2x − y = 1. What is y?

    Answer

Stretch Yourself

Mixed problems. Work out what kind of question it is before you start.

3 problems

  1. The System

    x + y = 10 and x − y = 4. What is x?

    Answer

  2. The Other Variable

    x + y = 10 and x − y = 4. What is y?

    Answer

  3. The Tickets

    Adult tickets cost 8 and child 5. 10 tickets cost 68. How many adult tickets?

    Answeradult tickets