Transcript x - ClassZone

EXAMPLE 1
Solve an equation with a variable on one side
Solve 4 x + 8 = 20.
5
4 x + 8 = 20
5
4 x = 12
5
x = 5 (12)
4
x = 15
Write original equation.
Subtract 8 from each side.
Multiply each side by 5 ,
the reciprocal of 4 . 4
5
Simplify.
ANSWER The solution is 15.
CHECK x = 15 in the original equation.
4 x + 8 = 4 (15) + 8 = 12 + 8 = 20
5
5
EXAMPLE 2
Write and use a linear equation
Restaurant
During one shift, a waiter earns wages of $30 and gets
an additional 15% in tips on customers’ food bills. The
waiter earns $105. What is the total of the customers’
food bills?
SOLUTION
Write a verbal model. Then write an equation. Write
15% as a decimal.
EXAMPLE 2
Write and use a linear equation
105 = 30 + 0.15x
75 = 0.15x
500 = x
Write equation.
Subtract 30 from each side.
Divide each side by 0.15.
ANSWER
The total of the customers’ food bills is $500.
GUIDED PRACTICE
for Examples 1 and 2
Solve the equation. Check your solution.
1.
4x + 9 = 21
ANSWER The solution is x = 3.
2.
7x – 41 = – 13
ANSWER The solution is x = 4.
3. – 3 x + 1 = 4
5
ANSWER The solution is 5.
GUIDED PRACTICE
for Examples 1 and 2
4. REAL ESTATE
A real estate agent’s base salary is $22,000 per year.
The agent earns a 4% commission on total sales. How
much must the agent sell to earn $60,000 in one year?
ANSWER
The agent must sell $950,000 in a year to each $ 60000