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hendricks_intermediate_algebra_1e_ch1_3

Section 2.3 Formulas and Applications 81 Troubleshooting Common Errors Some common errors associated with formulas are shown. Objective 5 ▶ Troubleshoot common errors. Objective 5 Examples A problem and an incorrect solution are given. Provide the correct solution and an explanation of the error. 5a. The supplement of an angle is 40° less than three times the measure of the angle. Find the measure of the angle. Incorrect Solution Correct Solution and Explanation The error was made in the representation x - 180 = 3x - 40 of the supplement of an angle. The -140 = 2x supplement is 180 - x. -70 = x 180 - x = 3x - 40 There is no solution since we can’t 220 = 4x have a negative angle. 55 = x The measure of the angle is 55°. 5b. Solve the equation for y: 3x - 4y=-12. Incorrect Solution Correct Solution and Explanation 3x - 4y=-12 When 3x is subtracted from both sides, the coefficient of y should remain negative. Also, in the last step the denominator of 4 must divide into each term. 3x - 4y=-12 -4y=-3x - 12 y = -3x - 12 -4 y = 3 4 x + 3 4y=-3x - 12 y = -3x - 12 4 y=-3x - 3 ANSWERS TO STUDENT CHECKS Student Check 1 a. 20° b. 60° c. 56° and 124° d. The measure of each angle is 110°. Student Check 2 a. A = 216 in.2, P = 60 in. b. A = 16π in.2, C = 8π in. c. A = 9 ft2 d. The distance is 383.1 m or 1256 ft. e. The length is 35 ft and the width is 179 ft. Student Check 3 a. A ≈ $28,211.98 b. P ≈ $74,725.82 c. 68°F d. 40°C Student Check 4 a. w = A l b. a = P - b - c c. h = 3V B d. y = 6x - 6 e. y=- 2 7 x - 2


hendricks_intermediate_algebra_1e_ch1_3
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