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© 3-8 NAME ______________________________________________ DATE ____________ PERIOD _____ 3-8 Skills Practice 1. 7t x, for t x t 2. e wp, for p 7 q 3. q r r, for r r 2 5. 7a b 15a, for a 8 x1 y 2 9. 7f g 5, for f f 7 5g 11. rt 2n y, for t 2n y t r 1. d rt, for r w 9v 4f n k 6. 5c d 2c, for c 8. m 3n 1, for n d c 12. bc 3g 2k, for c 2. 6w y 2z, for w t 3c 4y x m 4. 9s 5g 4u, for s 5. ab 3c 2d, for b 2d 3c b a 6. 2p kx q, for x 2 3 3 m c 8. h g d, for h 2 3 3 y (s v) 10. a q k, for a 9. y v s, for y 1m n 3 2k 3g c b 5p 6j 14. 8c 6j 5p, for c c 8 2z y w 6 3. mx 4y 3c, for x 7. m a a c, for m 7 rx 9 11. h, for x 5 bc x a 10. ax c b, for x d r 2 2 5h 9 x r 13. 2w y 7w 2, for w 4u 5g s 9 2p q x k 2 5 5 h (d g ) 3 4 4 a (k q) 2 3 2c 4 b 3 y5 14. 3 y 5 5, for 2 3b 4 12. c, for b 2 2y w 5 Write an equation and solve for the variable specified. 15. Three times a number s plus 4 times a number y is 1 more than 6 times the number s. Solve for s. 4y 1 3s 4y 6s 1; s 3 16. Five times a number k minus 9 is two thirds of a number j. Solve for j. xc 15. d, for x 2 p9 5 17. q, for p x c 2d xc 16. d, for c 2 p 5q 9 18. a, for b b 4z 7 2 3 5k 9 j; j (5k 9) c x 2d b 7a 4z 3 2 ELECTRICITY For Exercises 17 and 18, use the following information. The formula for Ohm’s Law is E IR, where E represents voltage measured in volts, I represents current measured in amperes, and R represents resistance measured in ohms. E R Write an equation and solve for the variable specified. 17. Solve the formula for R. 19. Five more than a number g is six less than twice a number h. Solve for g. 18. Suppose a current of 0.25 ampere flows through a resistor connected to a 12-volt battery. What is the resistance in the circuit? 48 ohms g 5 2h 6; g 2h 11 I MOTION For Exercises 19 and 20, use the following information. 20. One fourth of a number q is three more than three times a number w. Solve for q. 1 q 3w 3; q 12w 12 4 Glencoe Algebra 1 where r is the radius of the disk and T is the time it takes the point to travel once around the circle. 21. Eight less than a number s is three more than four times a number t. Solve for s. Glencoe/McGraw-Hill 19. Solve the formula for r. Tv 2 r 20. Suppose a merry-go-round is spinning once every 3 seconds. If a point on the outside edge has a speed of 12.56 feet per second, what is the radius of the merry-go-round? (Use 3.14 for .) 6 ft s 8 4t 3; s 4t 11 © 2 T In uniform circular motion, the speed v of a point on the edge of a spinning disk is v r, 181 Glencoe Algebra 1 © Glencoe/McGraw-Hill 182 Glencoe Algebra 1 (Lesson 3-8) A24 13. kn 4f 9v, for n e p Answers 7. x 2y 1, for y (Average) Solve each equation or formula for the variable specified. n 4. 4m n m, for m m 3 b a Practice ____________ PERIOD _____ Solving Equations and Formulas Solving Equations and Formulas Solve each equation or formula for the variable specified. Lesson 3-8 Glencoe/McGraw-Hill NAME ______________________________________________ DATE