Part B A different student claims that the expression 59.2xy is equivalent to the teacher’s expression. The student’s reasoning
1 answer:
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Answer:
-675
Step-by-step explanation:
The sum can be broken into parts that you know. Here, one of those parts is the sum of numbers 1 to n. That sum is given by n(n+1)/2.
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Another way to do this is to realize the sequence of numbers is an arithmetic sequence with a first term of 65 and a last term of 67-2·75 = -83.
The sum of an arithmetic sequence is found by multiplying the number of terms by their average value. Their average value is the average of the first and last terms.
The average value of those 75 terms is (65 +(-83))/2 = -9, so their sum is ...
75(-9) = -675
Given that:
Consider it is instead of 10 on two places.
is between 3 and 4. So, Beau thinks a good estimate for
is = 3.5.
Solution:
To find , Beau found 3² = 9 and 4² = 16.
He said that since 10 is between 9 and 16.
Since 10 is close to 9, therefore must be close to 3. So, Beau's estimate is high.
Now,
Since, 10 lies between 9.61 and 10.24, therefore must be lies between 3.1 and 3.2.
Therefore, the estimated value of is 3.15.