February 10, 2015
February 10, 2015
February 10, 2015
Ch. 2: Equations and Inequalities
2.2B Formulas
Objectives: 1) Solve formulas for one of its variables.
2) use dimensional analysis to convert units
Formula - An algebraic equation that relates 2 or more real-life
quantities.
Let's say you had the given data and wanted to find the missing
lengths, what would you do?
Area
Width
Length
50
10
?
44
4
?
32
8
?
21
7
?
Width
A=
Length
You may want to change the formula
so it's easier to work with given the
information.
Ex1: Solving for a specific variable...
Solve 3x - 2y = xz + 5 for x.
Ex2: Find the following temperatures in Fahrenheit.
56 C, 35 C, 20 C, 100 C given C= 5(F-32)
9
Solve for F
C= 5 (F-32)
9
Celsius
Fahrenheit
Use the same steps
that you have been using
to solve multi-step
equations... Isolate the
variable.
February 10, 2015
Let's try some more!
Solve the formulas for the given variable.
Example 3: Simple Interest
a) I=Prt solve for t.
b) Find the # of years it would
take $2800 to earn $504 at
4.5%.
Example 4: Perimeter
a) P=2L+2W solve for L.
b) Find the length of a
rectangular pen with 500ft. of
fencing and a width of 100ft.
Example 5: Distance
a) d=rt solve for t.
b) How long will it take to go
184 miles at a rate of 65mph?
Dimensional Analysis or Unit Analysis [Label Method]
The temperature within Earth's crust increases about 30ºC for each
kilometer of depth beneath the surface. If the temperature at Earth's
surface is 24ºC, at what depth would you expect the temperature to
be 114ºC?
1959
Where would that put us?
Recent research suggests that the Earth's inner core is 6,000ºC (1000ºC more than
previously thought). What is this in degrees Fahrenheit (ºF)?
C = (F-32) 5
Formula?
9