Lesson Page

Math A



Equations and formulas that have several variables (letters) are called literal equations.  Your job, usually, will be to solve the equation for one of the variables.  In other words, move all the letters away from the one you are solving for.  They go to the other side of the equal sign so that the one variable you are solving for stands alone. 

Example #1 

 Steps 
Solve for x:  
ax + b = c
     - b   -b 

 

 1. Move b
(the opposite of + is -)
ax = c - b

 

 2. Move a
(the opposite of  x  is )
 

3. X is what we are solving for and it stands alone.  Done.



Example #2 

 Steps 
Solve for h:  
A = ½ b h

     

 

 1. Move b by
2.  Move the ½ by multiplying by the reciprocal (2/1)
 

3. h is what we are  solving for and it  stands alone.  Done.




Application Problem

Brandon knows that his truck route from Illinois to Tennessee is 430 miles long.
He also knows that Distance = rate • time (D = rt)
How long will his route take if he averages a speed of 50 mi/hr? 
Solution: Steps:
solve for t (time)
 
substitute 430 in for D and 50 in for r and solve.
It will take Brandon 8.6 hours.


 

Mathematics A Exam   June 22, 1999
Part II question #22

Shoe sizes and foot length are related by the formula 
S = 3F - 24,
 where S represents the shoe size
 and F represents the length of the foot, in inches.

a.) Solve the formula for F.

Solution:

 Steps:
S = 3F - 24

 

  
S + 24 = 3F

 

 add 24 to both sides

 

 divide both sides by 3
Done.





Schultzkie