Practice and Problem-Solving Exercises

A Practice

See Problem 1.

Solve each system by graphing. Check your solution.

10. y = 2x

    y = − 2 x + 8 y equals negative 2 x plus 8

11. y = 1 2 x + 7 y = 3 2 x + 3 table with 2 rows and 1 column , row1 column 1 , y equals , 1 half , x plus 7 , row2 column 1 , y equals , 3 halves , x plus 3 , end table

12. y = 1 3 x + 1 y equals , 1 third , x plus 1

    y = − 3 x + 11 y equals negative 3 x plus 11

13. y = x − 4 y equals x minus 4

    y = − x y equals negative x

14. y = − x + 3 y equals negative x plus 3

    y = x + 1

15. 4 x − y = − 1 4 x minus y equals negative 1

    − x + y = x − 5 negative x plus y equals x minus 5

16. y = − 1 2 x + 2 y = 1 2 x + 6 table with 2 rows and 1 column , row1 column 1 , y equals negative , 1 half , x plus 2 , row2 column 1 , y equals , 1 half , x plus 6 , end table

17. 2 x − y = − 5 2 x minus y equals negative 5

    − 2 x − y = − 1 negative 2 x minus y equals negative 1

18. x = − 3 x equals negative 3

    y = 5

    See Problem 2.

19. Student Statistics The number of right-handed students in a mathematics class is nine times the number of left-handed students. The total number of students in the class is 30. How many right-handed students are in the class? How many left-handed students are in the class?

20. Plants A plant nursery is growing a tree that is 3 ft tall and grows at an average rate of 1 ft per year. Another tree at the nursery is 4 ft tall and grows at an average rate of 0.5 ft per year. After how many years will the trees be the same height?
21. Fitness At a local fitness center, members pay a $20 membership fee and $3 for each aerobics class. Nonmembers pay $5 for each aerobics class. For what number of aerobics classes will the cost for members and nonmembers be the same?

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