Rewrite Equations and Formulas

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

Literal Equation

An equation with two or more variables. An equation in which letters are used to

replace coefficients and constants of another equation.

Examples:

wlP

cbax

xx

rA

22

0321

2

Solving Literal Equations

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 literal equations

Solve ax + b = c for x. Then use the solution to solve 2x + 5 = 11

Step 1: Solve ax + b = c for xStep 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.

Two or more variables…

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 cm2 13 cm

Homework

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

32, 33