OBJECTIVE 6 Evaluate expressions involving variables.
Evaluating Expressions for Numerical ValuesEvaluate each expression for and
(a)
Substitute the given values= 331 - 12 + 41 - 2243 - 21 - (^324) for the variables.
13 x+ 4 y 21 - 2 m 2
x=-1,y=-2, m=-3.
EXAMPLE 6
54 CHAPTER 1 The Real Number System
NOW TRY
EXERCISE 6Evaluate for
and y=-3.
x=- 43 x^2 - 12
yNOW TRY ANSWER
- 12
Use parentheses around substituted
negative values to avoid errors.(b)
Substitute.Apply the exponents.
Multiply.=- 10 Subtract.
= 2 - 12
= 2112 - 3142
= 21 - 122 - 31 - 222
2 x^2 - 3 y^2 Think: 1 - 222 =- 21 - 22 = 4
(c)
Substitute.Apply the exponent.Multiply.= or - 5 Add, and then divide. NOW TRY
15
- 3
,
=
16 + 1 - 12
- 3
=
4142 + 1 - 12
- 3
=
41 - 222 + 1 - 12
- 3
4 y^2 + x
m
Translating Words and Phrases (Multiplication)Write a numerical expression for each phrase, and simplify the expression.
(a)The product of12 and the sum of 3 and 6
simplifies to , or
(b)Twicethe difference between 8 and 4
238 - 1 - 424 simplifies to 23124 , or 24.
-
12 33 + 1 - 624 12 3 - 34 - 36.
-
EXAMPLE 7
Numerical Expression
Word or Phrase Example and Simplification
Product of The product of 5 and 2 , or 10
Times 13 times 4 , or
Twice (meaning “2 times”) Twice 6 , or 12
Of (used with fractions) of 10 , or 5
Percent of 12 % of 16 or
As much as^23 as much as 30 23 1302 ,or 20- 0.12 1 - 162 , -1.92
1
2 1102
1
22162- 131 - 42 - 52
- 51 - 22
Multiply.
Add inside the brackets.=- 66 Multiply.
= 3 - 1146
= 3 - 3 + 1 - 824364
OBJECTIVE 7 Translate words and phrases involving multiplication and
division. The table gives words and phrases that indicate multiplication.
Think: 1 - 122 =- 11 - 12 = 1http://www.ebook777.com
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