M098
Carson Elementary and Intermediate Algebra 3e
Section 2.4
Objectives
1.
Isolate a variable in a formula using the addition and multiplication principles
Vocabulary
Prior Knowledge
Solving linear equations
New Concepts
1. Formulas
The same process used to solve linear equations can also be used to isolate a variable in a formula.
Example 1: Solve for the variable in each formula
1.
3m  b  y; for m
2.
19  2L  2w; for w
3.
q
1.
rs
 p; for p
2
2.
3.
yb
3
19  2L
w 
2
rs
p 
q
2
m
If the formula contains a fraction, clear it first.
Example 2:
a b
 3
4 6
12
There are 3 terms and the LCD is 12.
a
b
 12  123
4
6
Multiply each term by 12.
3a + 2b = 36
Reduce fractions to eliminate the denominators.
3a = -2b + 36
Subtract 2b from both sides.
a
V Zabrocki 2010
Solve for a.
2b  36
3
Divide both sides by 3.
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