Chapter Summary and Review continued
3.5
Examples on
pp. 157–159
MORE ON LINEAR EQUATIONS
EXAMPLE
You can use a verbal model to write and solve linear equations.
You are making sandwiches to sell at a fundraiser. It costs $.90
to make each sandwich plus a one-time cost of $24 for packaging. You plan to
sell each sandwich for $2.50. Write and solve an equation to find how many
sandwiches you need to sell to break even.
FUNDRAISER
Cost to make p Number of Cost of Price of p Number of
sandwiches
sandwiches
sandwich
sandwich
packaging
VERBAL
MODEL
LABELS
Cost to make sandwich 0.90
(dollars)
Cost of packaging 24
(dollars)
Number of sandwiches x
Price of sandwich 2.50
(dollars)
0.90 p x 24 2.50 p x
ALGEBRAIC
MODEL
24 1.6x
15 x
ANSWER You need to sell 15 sandwiches to break even, or recover your costs.
19. TOMATOES One tomato plant is 12 inches tall and grows 1 inch per week.
Another tomato plant is 6 inches tall and grows 2 inches per week. Write and
solve an equation to find when the plants will be the same height.
3.6
Examples on
pp. 163–165
SOLVING DECIMAL EQUATIONS
EXAMPLE
For some equations, only an approximate solution is required.
3.45m 2.93m 2.95
Write original equation.
6.38m 2.95
Add 2.93m to each side.
m ≈ 0.462382445
Divide each side by 6.38.
Use a calculator to get an approximate solution.
m ≈ 0.46
Round to nearest hundredth.
Solve the equation. Round the result to the nearest hundredth.
20. 3x 4 3
21. 5x 9 18x 23
22. 13.7t 4.7 9.9 8.1t
Chapter Summary and Review
191