3.6 U SING F ORMULAS AND L ITERAL E QUATIONS Objectives: Solve literal equations for specific variable. Use formulas to solve problems. Standard Addressed: D: 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.
E X. 1
S OLVING FOR A V ARIABLE With some literal equations and formulas you will need to solve the equation for one variable in terms of the other variables.
E X. 2
E X. 3
E X. 4 S OLVE EACH EQUATION FOR THE INDICATED VARIABLE. A. y = mx + b, for b y – mx = b B. 3 x + 4 y = 12, for y 4 y = 12 – 3x y = 3 – 3/4x C. d = k + s, for s d – k = s D. p = 6 x + 2 z, for z p – 6x = 2z p/2 – 3x = z
E X. 5 A. J OSEPHINE HAS 396 LINEAR FEET OF CHICKEN WIRE AND IS PUTTING A FENCE UP ON HER SMALL FARM TO FENCE IN HER CHICKEN. S HE WANTS THE LENGTH OF THE PEN TO BE TWICE THE WIDTH. F IND THE DIMENSIONS OF THE PEN. 396 = 2w + 2w + w + w 396 = 6w 66 = w L = 132
B. J OY HAS 480 FEET OF CHICKEN WIRE AND IS BUILDING A PEN. S HE WANTS THE LENGTH OF THE PEN TO BE 3 TIMES THE WIDTH. F IND THE DIMENSIONS OF THE PEN. 480 = 3w + 3w + w + w 480 = 8w W = 6 L = 180
E X. 6
E X. 7