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LECTURE 4 IMA 101: Basic Math 6/17/2010 1 IMA101: Basic Mathematics
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Lecture Outline 6/17/2010 IMA101: Basic Mathematics 2 HW/Journal overview Wrapping up mixed numbers Decimals Square roots
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Mixed Numbers: Addition 6/17/2010 IMA101: Basic Mathematics 3
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Mixed Numbers: Subtraction 6/17/2010 IMA101: Basic Mathematics 4 Remember to distribute the subtraction sign to the whole part and the fraction of the subtracted mixed number
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Complex Fractions 6/17/2010 IMA101: Basic Mathematics 5 Recall: A fraction is just a number (numerator) divided by another number (denominator) Simplify the following:
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Order of Operations 6/17/2010 IMA101: Basic Mathematics 6
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Decimals 6/17/2010 7 IMA101: Basic Mathematics
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Introduction to Decimals Decimals as fractions -1.5 8361.2759 Fractions as Decimals 5/10 3/4 1/5 6/17/2010 8 IMA101: Basic Mathematics
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Understanding Decimals 6/17/2010 IMA101: Basic Mathematics 9 Place values Writing whole numbers as decimals 42 Comparing two decimals 1.992.99 1.9991.99 -0.58-0.57
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Rounding decimals Similar to rounding whole numbers >,=5 1 <5 0 3.14159265 Round to the nearest… Tenth Hundredth Thousandth Ten-thousandth … 6/17/2010 10 IMA101: Basic Mathematics
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Addition and Subtraction with Decimals Same as with whole numbers Line up the decimal points, and pull it down to the result Examples 382.5 – 227.1 = 2.56 – (-4.4) = 6/17/2010 11 IMA101: Basic Mathematics
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Dividing to get a decimal 6/17/2010 IMA101: Basic Mathematics 12 5/8 use long division
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Multiplication with decimals 6/17/2010 IMA101: Basic Mathematics 13 IGNORE the decimal point First multiply by the numbers, just like you would a whole number Then count the number of places (in BOTH numbers) Move the decimal of the result over that number of places Examples: 5.9 * 0.21.4 * 0.006
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Multiplication with decimals 6/17/2010 IMA101: Basic Mathematics 14 Student Practice: 67.164 * 31 46.28 *.0098 6981 *.097
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Decimals: Multiplication by 10 6/17/2010 IMA101: Basic Mathematics 15 Decimals represent fractions of 10, 100, 1000… So multiplying a decimal by 10 means we just divide the denominator of each fraction by 10 8361.2759 Notice: we just move the decimal point to the right by 1
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Decimals: Multiplication by powers of 10 6/17/2010 IMA101: Basic Mathematics 16 Count the number of zeros and move the decimal point to the right that many spaces 3.14159265 * 10 = 3.14159265 * 100 = 3.14159265 * 1000 = 3.14159265 * 10000 =
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Dividing a Decimal by a whole number 6/17/2010 IMA101: Basic Mathematics 17 Long division: move decimal point in the same spot 71.68/ 28
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Dividing a Decimal by a Decimal 6/17/2010 IMA101: Basic Mathematics 18 Move decimal point over (for BOTH numbers) until you are dividing by a whole number. 0.2592/ 0.36
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Dividing by a Decimals 6/17/2010 IMA101: Basic Mathematics 19 Student Practice: -5.714/ 2.40.02201/ 0.08 12.243 / 0.900.003164/0.04
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Dividing a Decimal by 10 6/17/2010 IMA101: Basic Mathematics 20 Same idea as multiplication, except this time we move the decimal point to the _____. Example 9.0 / 10 = 4592.13 / 10 =
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Fractions and Decimals: Revisited 6/17/2010 IMA101: Basic Mathematics 21 Writing fraction as the equivalent decimal Use long division with decimals 5/8
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Repeating decimals 6/17/2010 IMA101: Basic Mathematics 22 Numbers that are never factors of a power of 10 (i.e. whose factors are not 2 or 5) do not form FINITE decimals Use a bar to indicate repeated digits Example: 1/3
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Repeating Decimals 6/17/2010 IMA101: Basic Mathematics 23 Student examples 1/114/7 2/94/13 [Rounding repeating decimals]
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Fractions and Decimals 6/17/2010 IMA101: Basic Mathematics 24 Decide if it’s easiest to work in terms of decimals or in terms of fractions Are the decimals easily divided by the denominator? (3/4) * 0.88 + (1/3) * 6.60
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IMA101: Basic Mathematics 6/17/2010 25 Square roots
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6/17/2010 IMA101: Basic Mathematics 26 Recall: 9 2 = 81 81 is a perfect square 9 is the Square ROOT of 81 √81 = 9 Recall: -9 * -9 = 81 so -9 is also a square root of 81 We denote this as - √81 = -9 -9 * 9 = -81, but since -9≠ 9, -81 is NOT a square We can NEVER take the square root of a negative number. Why?
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Perfect Squares 6/17/2010 IMA101: Basic Mathematics 27 3 2 = 99 2 =81
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Perfect squares: memorize these 6/17/2010 IMA101: Basic Mathematics 28 123456789101112 1123456789101112 224681012141618202224 3369121518212427303336 44812162024283236404448 551015202530354045505560 661218243036424854606672 771421283542495663707784 881624324048566472808896 9918273645546372819099108 10 2030405060708090100110120 11 2233445566778899110121132 12 24364860728496108120132144
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Properties of Square Root 6/17/2010 IMA101: Basic Mathematics 29 Note that we cannot “distribute” the square root when we add or subtract two terms √ 15 = √ (4+9) ≠ √4 + √9 = 2 + 3 = 5 However, when we multiply or divide the square root 6 = 2*3 = (√4) * (√ 9) =√ (4*9) = √ (36) = 6
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How to find the square root of a number 6/17/2010 IMA101: Basic Mathematics 30 Using prime factorization √400 √2304 = √3136=
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