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messersmith_power_introductory_algebra_1e_ch4_7_10

YOU TRY 3 Solve. a) (z 10)2 7 b) (4d 1)2 16 c) (5p 2)2 27 3 Solve a Formula for a Specific Variable Sometimes, we need to use the square root property to solve a formula for a specifi c variable. The formula for the volume, V, of a right circular cone is V 1 3 pr2h, where r is the radius of the base and h is the height. Find the radius of the base of a right circular cone if it is 9 in. high and its volume is 12p in3. Solution We will substitute the given values into the formula and solve for r. V 1 3 pr2h 12p 1 3 pr2(9) Substitute 12 for V and 9 for h. 12p 3pr2 Multiply. 12p 3p 3pr2 3p Divide both sides by 3. 4 r2 Simplify. 14 r Square root property 2 r Simplify. The radius of the cone cannot be negative, so we discard r 2. The radius is 2 in. EXAMPLE 4 In-Class Example 4 Use the formula in Example 4 to find the radius of the base of a cone with a height of 12 in. and a volume of 36 in3. Answer: 3 in. YOU TRY 4 The formula for the volume, V, of a right circular cylinder is V r2h, where r is the radius and h is the height. Find the radius of a cylinder if it is 15 cm high and its volume is 240 cm3. ANSWERS TO YOU TRY EXERCISES 1) a) {5, 5} b) 5217, 2176 c) 5110, 1106 d) 2) {5, 1} 3) a) 510 17, 10 176 b) e 5 4 , 3 4 f c) e 2 313 5 , 2 313 5 f 4) 4 cm 610 CHAPTER 10 Quadratic Equations www.mhhe.com/messersmith


messersmith_power_introductory_algebra_1e_ch4_7_10
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