Practice and Problem-Solving Exercises

A Practice

See Problem 1.

Solve each system by graphing.

8. y = x 2 + 1 y = x + 1 table with 2 rows and 1 column , row1 column 1 , y equals , x squared , plus 1 , row2 column 1 , y equals x plus 1 , end table
9. y = x 2 + 4 y = 4 x table with 2 rows and 1 column , row1 column 1 , y equals , x squared , plus 4 , row2 column 1 , y equals 4 x , end table
10. y = x 2 − 5 x − 4 y = − 2 x table with 2 rows and 1 column , row1 column 1 , y equals , x squared , minus 5 x minus 4 , row2 column 1 , y equals negative 2 x , end table
11. y = x 2 + 2 x + 1 y = x + 1 table with 2 rows and 1 column , row1 column 1 , y equals , x squared , plus 2 x plus 1 , row2 column 1 , y equals x plus 1 , end table
12. y = x 2 + 2 x + 5 y = − 2 x + 1 table with 2 rows and 1 column , row1 column 1 , y equals , x squared , plus 2 x plus 5 , row2 column 1 , y equals negative 2 x plus 1 , end table
13. y = 3 x + 4 y = − x 2 + 4 table with 2 rows and 1 column , row1 column 1 , y equals 3 x plus 4 , row2 column 1 , y equals negative , x squared , plus 4 , end table

See Problem 2.

Solve each system using elimination.

14. y = − x + 3 y = x 2 + 1 table with 2 rows and 1 column , row1 column 1 , y equals negative x plus 3 , row2 column 1 , y equals , x squared , plus 1 , end table
15. y = x 2 y = x + 2 table with 2 rows and 1 column , row1 column 1 , y equals , x squared , row2 column 1 , y equals x plus 2 , end table
16. y = − x − 7 y = x 2 − 4 x − 5 table with 2 rows and 1 column , row1 column 1 , y equals negative x minus 7 , row2 column 1 , y equals , x squared , minus 4 x minus 5 , end table

17. Sales The equations below model the numbers y of two portable music players sold x days after both players were introduced. On what day(s) did the company sell the same number of each player? How many players of each type were sold?

    Music Player A: y = 48 x + 20 y equals 48 x plus 20

    Music Player B: y = − x 2 + 200 x + 20 y equals negative . x squared , plus 200 . x plus 20

See Problem 3.

Solve each system using substitution.

18. y = x 2 − 2 x − 6 y = 4 x + 10 table with 2 rows and 1 column , row1 column 1 , y equals , x squared , minus 2 x minus 6 , row2 column 1 , y equals 4 x plus 10 , end table
19. y = 3 x − 20 y = − x 2 + 34 table with 2 rows and 1 column , row1 column 1 , y equals 3 x minus 20 , row2 column 1 , y equals negative , x squared , plus 34 , end table
20. y = x 2 + 7 x + 100 y + 10 x = 30 table with 2 rows and 1 column , row1 column 1 , y equals , x squared , plus 7 x plus 100 , row2 column 1 , y plus 10 x equals 30 , end table
21. − x 2 − x + 19 = y x = y + 80 table with 2 rows and 1 column , row1 column 1 , negative , x squared , minus x plus 19 equals y , row2 column 1 , x equals y plus 80 , end table
22. 3 x − y = − 2 2 x 2 = y table with 2 rows and 1 column , row1 column 1 , 3 x minus y equals negative 2 , row2 column 1 , 2 , x squared , equals y , end table
23. y = 3 x 2 + 21 x − 5 − 10 x + y = − 1 table with 2 rows and 1 column , row1 column 1 , y equals 3 , x squared , plus 21 x minus 5 , row2 column 1 , negative 10 x plus y equals negative 1 , end table

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