204 algebra De mystif ieD
- 0.01(2x + 3) − 0.003 = 0.11x
Multiply both sides by 10^3 = 1000.
10000012 30003 1000011
10000012[.().] (. )
[.(xx
x+− =
+ 33 1000 0 003 110
10000012 33110
1)] (. )
[(. )]( )−=
+−=x
xx
002 33110
20 30 3 110
20 27 110
20 20()xx
xx
xx
xx+−=
+−=
+=
−−
227 90
27
90
3
10
03====xxx. x
Formulas
At times, math students are given a formula such as I = Prt and asked to solve
for one of the variables; that is, to isolate that particular variable on one side of
the equation. In I = Prt, the equation is solved for I. The method used earlier
for solving for x works on these, too. Many people are confused by the presence
of multiple variables. The trick is to think of the variable for which you are try-
ing to solve as x and all of the other variables as fixed numbers. For instance, if
you were asked to solve for r in I = Prt, think of how you would solve something
of the same form with numbers, say 100 = (500)(x)(2):100 500 2
100 500 2
100
500 2=
==()()()
[( )( )]()().x
xx