Practice and Problem-Solving Exercises

A Practice

See Problem 1.

Write an algebraic expression that models each word phrase.

10. four more than a number b
11. the product of 8 and the sum of a number x and 3
12. the quotient of the difference between 5 and a number n, and 2

See Problem 2.

Write an algebraic expression that models each situation.

13. Jenny had $130, but she is spending $10 per week.
14. The piggy bank contained $25, and $1.50 is added each day.
15. You had 250 minutes left on your cell phone, and you talk an hour a week.

See Problem 3.

Evaluate each expression for the given values of the variables.

16. 4 a + 7 b + 3 a − 2 b + 2 a ; a = − 5 4 eh plus 7 b plus 3 eh minus 2 b plus 2 eh semicolon eh equals negative 5  and b = 3
17. − k 2 − ( 3 k − 5 n ) + 4 n ; k = − 1  and  n = − 2 negative , k squared , minus open 3 k minus 5 n close plus 4 n semicolon k equals negative 1 , and , n equals negative 2
18. − 5 ( x + 2 y ) + 15 ( x + 2 y ) ; x = 7  and  y = − 7 negative 5 open x plus 2 y close plus 15 open x plus 2 y close semicolon x equals 7 , and , y equals negative 7
19. 4 ( 2 m − n ) − 3 ( 2 m − n ) ; m = − 15  and  n = − 18 4 open 2 m minus n close minus 3 open 2 m minus n close semicolon m equals negative 15 , and , n equals negative 18

Physics The expression 16 t 2 16 , t squared  models the distance in feet that an object falls during the first t seconds after being dropped. What is the distance the object falls during each time?

20. 0.25 second
21. 0.5 second
22. 2 seconds
23. 10 seconds

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