Page 505 - Algebra 1

Application: Technology
The thermostat in a classroom is set at 21°C. The thermostat will turn on (or off ) if the recorded temperature is ±1.2°C of this setting. What are the maximum and minimum temperatures for this classroom?
SOLUTION
Understand The thermostat will turn on or off if the difference between the recorded temperature, x, and the set temperature, 21°C, is 1.2° or -1.2°. This difference (x - 21) can be thought of as the distance between the maximum (or minimum) temperature and the set temperature.
Plan Thedistancebetweenthethermostatsettingandthemaximum(or minimum) temperature can be expressed by ⎪x - 21 = 1.2.
Solve ⎪x-21 =1.2
x - 21 = +1.2 or x - 21 = -1.2
x= 22.2 x=19.8
The solution is {22.2, 19.8}. With the thermostat set at 21°C, the temperature in the room could rise to a maximum of 22.2°C or fall to a minimum of 19.8°C.
Example
4
Check 21°C+1.2°C=22.2°C
21°C–1.2°C=19.8°C
c. 4⎪y⎪=24 (Ex 2)
f. ⎪x-5⎪=-1 (Ex 3)
Lesson Practice
Solve.
a.
(Ex 1)
d.
(Ex 2)
g.
(Ex 4)
⎪x⎪=11 5⎪z-3⎪=20
b. ⎪q+3⎪=6 (Ex 1)
e. ⎪x-5⎪+3=3 (Ex 3)
Agriculture A strawberry grower ships berries to a processing plant
in 30-pound cases. The plant will not accept cases that differ from this weight by more than ±0.4 pound. Write and solve an absolute-value equation to find the minimum and maximum weights that the processing plant will accept.
Practice
Distributed and Integrated
Factor.
1. x2 +12x-28
(72)
3. 18+x2 +11x (72)
Solve.
*5 n =13
(74)
2. 15x+50+x2 (72)
*4. 3x-18+x2 (72)
*6 Solve x+7 =3. (74)
490 Saxon Algebra 1