The series' value is maximized if the sum only consists of positive terms. Notice that each term in the sum takes the form 4<em>n</em> + 1 for integer <em>n</em>. This means the smallest positive integer that the sum can involve is 1, so the maximum value is
<em>S</em> = 29 + 25 + 21 + … + 9 + 5 + 1
Reversing the order of terms gives the same sum,
<em>S</em> = 1 + 5 + 9 + … + 21 + 25 + 29
Adding terms in the same positions gives us twice this sum,
2<em>S</em> = (29 + 1) + (25 + 5) + (21 + 9) + … + (1 + 29)
Notice how each grouped sum adds to 30. There are 8 terms in the sum, since 4<em>n</em> + 1 = 29 when <em>n</em> = 8. So
2<em>S</em> = 8 × 30 = 240 ===> <em>S</em> = 120
<span>The ratio of all books to used books = all books ÷ used books = 15 / (15-6) = 5/3
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<span> The ratio of new books to used books = new books ÷ used books = 6 / 9 = 2/3
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I hope that
helps!
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Answer:A ratio compares two numbers or two quantities that are measured with the same unit. The ratio of a to b is written a to b,ab,ora:b. ... When a ratio is written in fraction form, the fraction should be simplified. If it is an improper fraction, we do not change it to a mixed number.
Step-by-step explanation:
A ratio compares two numbers or two quantities that are measured with the same unit. The ratio of a to b is written a to b,ab,ora:b. ... When a ratio is written in fraction form, the fraction should be simplified. If it is an improper fraction, we do not change it to a mixed number.
Answer:
C-10
A-90
B-10
Step-by-step explanation:
For rounding off to nearest tens, we compare the last digit.
<span>Anna learns in her science class that the human eye blinks an average of 4,200,000 times a year. What is this number expressed in scientific notation?</span>
