# 2 6 Solving Literal Equations for a Variable

2 -6 Solving Literal Equations for a Variable Preview Warm Up California Standards Lesson Presentation

2 -6 Solving Literal Equations for a Variable Warm Up Solve each equation. 1. 5 + x = – 2 – 7 2. 8 m = 43 3. 19 4. 0. 3 s + 0. 6 = 1. 5 3 5. 10 k – 6 = 9 k + 2 8

2 -6 Solving Literal Equations for a Variable California Standards Extension of 5. 0 Students solve multistep problems, including word problems, involving linear equations and linear inequalities in one variable and provide justification for each step.

2 -6 Solving Literal Equations for a Variable Vocabulary formula literal equation

2 -6 Solving Literal Equations for a Variable A formula is an equation that states a rule for a relationship among quantities. In the formula d = rt, d is isolated. You can "rearrange" a formula to isolate any variable by using inverse operations. This is called solving for a variable.

2 -6 Solving Literal Equations for a Variable Solving for a Variable Step 1 Locate the variable you are asked to solve for in the equation. Step 2 Identify the operations on this variable and the order in which they are applied. Step 3 Use inverse operations to undo operations and isolate the variable.

2 -6 Solving Literal Equations for a Variable Additional Example 1: Application The formula C = d gives the circumference of a circle C in terms of diameter d. The circumference of a bowl is 18 inches. What is the bowl's diameter? Leave the symbol in your answer. The question asks for diameter, so first solve the formula C = d for d. Locate d in the equation. Since d is multiplied by , divide both sides by to undo the multiplication.

2 -6 Solving Literal Equations for a Variable Additional Example 1 Continued The formula C = d gives the circumference of a circle C in terms of diameter d. The circumference of a bowl is 18 inches. What is the bowl's diameter? Leave the symbol in your answer. Now use this formula and the information given in the problem. The bowl's diameter is inches.

2 -6 Solving Literal Equations for a Variable Helpful Hint A nonzero number divided by itself equals 1. For t ≠ 0,

2 -6 Solving Literal Equations for a Variable Check It Out! Example 1 Solve the formula d = rt for t. Find the time in hours that it would take Van Dyk to travel 26. 2 miles if his average speed was 18 miles per hour. Round to the nearest hundredth. d = rt Locate t in the equation. Since t is multiplied by r, divide both sides by r to undo the multiplication. Now use this formula and the information given in the problem.

2 -6 Solving Literal Equations for a Variable Check It Out! Example 1 Continued Solve the formula d = rt for t. Find the time in hours that it would take Van Dyk to travel 26. 2 miles if his average speed was 18 miles per hour. Van Dyk’s time was about 1. 46 hours.

2 -6 Solving Literal Equations for a Variable Additional Example 2 A: Solving Formulas for a Variable The formula for the area of a triangle is A = bh, where b is the length of the base, and h is the height. Solve for h. Locate h in the equation. Since bh is multiplied by sides by (multiply by the multiplication. 2 A = bh Simplify. , divide both , to undo

2 -6 Solving Literal Equations for a Variable Additional Example 2 A Continued The formula for the area of a triangle is A = bh, where b is the length of the base, and is the height. Solve for h. 2 A = bh Since h is multiplied by b, divide both sides by b to undo the multiplication.

2 -6 Solving Literal Equations for a Variable Remember! Dividing by a fraction is the same as multiplying by the reciprocal.

2 -6 Solving Literal Equations for a Variable Additional Example 2 B: Solving Formulas for a Variable Solve the formula for a person’s typing speed for e. Locate e in the equation. Since w– 10 e is divided by m, multiply both sides by m to undo the division. ms = w – 10 e –w –w ms – w = – 10 e Since w is added to – 10 e, subtract w from both sides to undo the addition.

2 -6 Solving Literal Equations for a Variable Additional Example 2 B Continued Solve the formula for a person’s typing speed for e. ms – w = – 10 e Since e is multiplied by – 10, divide both sides by – 10 to undo the multiplication.

2 -6 Solving Literal Equations for a Variable Check It Out! Example 2 The formula for an object’s final velocity is f = i – gt, where i is the object’s initial velocity, g is acceleration due to gravity, and t is time. Solve for i. f = i – gt +gt f + gt = i Locate i in the equation. Since gt is subtracted from i, add gt to both sides to undo the subtraction.

2 -6 Solving Literal Equations for a Variable A formula is a type of literal equation. A literal equation is an equation with two or more variables. To solve for one of the variables, use inverse operations.

2 -6 Solving Literal Equations for a Variable Additional Example 3: Solving Literal Equations A. Solve x + y = 15 for x. x + y = 15 –y –y x = 15 – y B. Solve pq = x for q. pq = x Locate x in the equation. Since y is added to x, subtract y from both sides to undo the addition. Locate q in the equation. Since q is multiplied by p, divide both sides by p to undo the multiplication.

2 -6 Solving Literal Equations for a Variable Check It Out! Example 3 a Solve 5 – b = 2 t for t. 5 – b = 2 t Locate t in the equation. Since t is multiplied by 2, divide both sides by 2 to undo the multiplication.

2 -6 Solving Literal Equations for a Variable Check It Out! Example 3 b Solve for V Locate V in the equation. VD = m Since m is divided by V, multiply both sides by V to undo the division. Since V is multiplied by D, divide both sides by D to undo the multiplication.

2 -6 Solving Literal Equations for a Variable Lesson Quiz: Part I Solve for the indicated variable. 1. for h 2. P = R – C for C C=R–P 3. 2 x + 7 y = 14 for y 4. for m 5. for C m = x(k – 6) C = Rt + S

2 -6 Solving Literal Equations for a Variable Lesson Quiz: Part II Euler’s formula, V – E + F = 2, relates the number of vertices V, the number of edges E, and the number of faces F of a polyhedron. 6. Solve Euler’s formula for F. F = 2 – V + E 7. How many faces does a polyhedron with 8 vertices and 12 edges have? 6

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