Transcript Slide 1

Lesson 3-8:
Solving Equations and
Formulas
Objectives
- I can solve equations and formulas that
have more than one variable for any given
variable
Seriously……..
Why don’t you
have graph paper
yet???
Example 1
Solve 5b + 12c = 9 for b.
5b + 12c = 9
– 12c
– 12c
5b = 9 – 12c
5b 9  12c

5
5
9  12c
b
5
Example 2
Solve 7x – 2z = 4 – xy for x.
7x – 2z = 4 – xy
+ xy
+ xy
7x – 2z + xy = 4
+ 2z
+ 2z
7x + xy = 4 + 2z
x(7 + y) = 4 + 2z
Example 2
Solve 7x – 2z = 4 – xy for x.
7x – 2z = 4 – xy
+ xy
+ xy
7x – 2z + xy = 4
+ 2z
+ 2z
7x + xy = 4 + 2z
x(7 + y) = 4 + 2z
(7 + y) (7 + y)
4  2z
x 
7y
Example 3
A car’s fuel economy E (miles per gallon) is
given by the formula E  mg , where m is the
number of miles driven and g is the number
of gallons of fuel used.
a) Solve the formula for m.
m
E
g
mæ g ö
g ( E) = ç ÷
g è1ø
gE = m
or
m= gE
Example 3
A car’s fuel economy E (miles per gallon) is
given by the formula E  mg , where m is the
number of miles driven and g is the number
of gallons of fuel used.
b) If Claudia’s car has an average fuel
consumption of 30 miles per gallon and she
used 9.5 gallons, how far did she drive?
m= gE
m  285 miles
m= (9.5)(30)
Homework
Pgs. 168-169: 14-32 Evens,
34-39 All