Lesson 3.8
OBJ: To recognize and solve literal equations; to rewrite equations and formulas.

 An equation with two or more variables.
 An equation in which letters are used to replace coefficients and constants of another equation.
 Examples:
A
  r
2 x
1 x
2 ax

 b
3

 c
0
P

2 l

2 w

 Solving equations for one variable in terms of the other variables without substituting any values.
 Examples:
 Solve V =lwh for h.
 Solve A = p +prt for r.
 Solve A = p + prt for p.
**Use the same rules for solving equations. The only difference is that it is not numbers, it is only variables.

 Solve ax + b = c for x. Then use the solution to solve 2x + 5 = 11
 Step 1: Solve ax + b = c for x
 Step 2: Use the solution to solve
2x + 5 = 11.
 The solution of 2x + 5 = 11 is 3.
 Example: Solve p + qx = r for x. Then use the solution to solve 3+5x = -7.

 Write -2x + 3y = 6 so that y is a function of x.
 This means solve for y.
 Write 12 = 9x + 3y so that y is a function of x.
 Write 14 = 7y – 6x so that y is a function of x.

Solve and use Geometric Formulas
 The area for a rectangle is given by the formulas A = lw, where l is the length and w is the width.
 Solve the formula for the length l.
 Use the rewritten formula to find the length of this rectangle.
A = 351 cm 2 13 cm

 Text p. 187- 188

#’s 3-6, 12 – 18 evens, 20 -22, 24, 26, 27,
32, 33