3.6 USING FORMULAS AND LITERAL EQUATIONS

Objectives: Solve literal equations for specific variable. Use formulas to solve problems.

 

Standard Addressed: 2.8.11D: Formulate equations to model routine and non-routine problems.

An equation that involves 2 or more variables is

called a literal equation. A formula is a literal equation that states a rule for a

relationship among quantities.

EX. 1

SOLVING FOR A VARIABLE

With some literal equations and formulas you will need to solve the equation for one variable in terms of the other variables.

EX. 2

EX. 3

EX. 4 SOLVE EACH EQUATION FOR THE INDICATED VARIABLE.

A. y = mx + b, for b y – mx = b

B. 3x + 4y = 12, for y 4 y = 12 – 3x

y = 3 – 3/4x

C. d = k + s, for sd – k = s

D. p = 6x + 2z, for zp – 6x = 2zp/2 – 3x = z

EX. 5 A. JOSEPHINE HAS 396 LINEAR FEET OF CHICKEN WIRE AND IS PUTTING A FENCE UP ON HER SMALL FARM TO FENCEIN HER CHICKEN. SHE WANTS THE LENGTH OF THE PEN TO BE TWICE THE WIDTH. FIND THE DIMENSIONS OF THE PEN.

396 = 2w + 2w + w + w 396 = 6w 66 = w

L = 132

 B. JOY HAS 480 FEET OF CHICKEN WIRE AND IS BUILDING A PEN. SHE WANTS THE LENGTH OF THE PEN TO BE 3 TIMES THE WIDTH. FIND THE DIMENSIONS OF THE PEN.

480 = 3w + 3w + w + w 480 = 8w W = 6

L = 180

EX. 6

EX. 7