Math on the Mind

Solving Two-Step Equations

Unit 4, Lesson 2 Algebra A

Two-Step Equations • Draw a line. • Locate the variable.

• Add or subtract the number without a variable.

• Multiply or divide to eliminate the number with the variable.

Examples 2

x

  4 4 2 

x

2

x

     20  12 4 24  2

x

3   7

x

7  3

x

   1  7  6  1 18

Example: Solve 13 = + 5 3 – 5 – 5 8 =

y

3 x 3 x 3 24 =

y

Example:

c

Solve 8 = + 4 – 4 – 4 4 =

c

24 x 24 x 24 96 =

c

Balancing Act!

• http://nlvm.usu.edu/en/nav/frames_asid_201_g_3_t_2.html?

open=instructions&from=category_g_3_t_2.html

Example: A music store sells a used guitar for $120. This is $25 more than ½ the cost of a new guitar of the same brand. What is the cost of a new guitar?

Define: Let

c

= the cost of the new guitar Write: $120 = $25 + •

c

1 120 = 25 +

c

– 25 – 25 95 = 2

c

x 2 x 2 190 =

c

The new guitar costs $190.

Example You order iris bulbs from a catalog. Iris bulbs cost $.90 each. The shipping charge is $2.50. If you have $18.50 to spend, how many iris bulbs can you order?

Define: Let Write: 0.90

•

b b

= the number of bulbs you order.

+

2.50 = 18.50

– 2.50 – 2.50

0.90

b

0.90

= 16 0.90

You can order 17 bulbs.

b

= 17.7

THINK BEFORE YOU ROUND!

What is reasonable? You can only order whole iris bulbs. Since 18 bulbs would cost 18 • 0.90 = 16.20 plus $2.50 for shipping, which is more than $18.50, you can only afford to order 17 bulbs.

BrainPop Recap!

• http://www.brainpop.com/math/algebra/twostepequations/

Video Tutor • http://phschool.com/webcodes10/index.cfm?fuseaction=hom e.gotoWebCode&wcprefix=ate&wcsuffix=0301