How much money is 3/4 of a dollars plus 3/10 of a dollar?
2 answers:
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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
For this case we must factor the following polynomial:
We can take common factor x:
To factor the expression within the parenthesis, we must find two numbers that when multiplied give 49 and when added together, 14 are obtained. These are: 7 and 7.
Thus, the expression is factored as:
Answer: