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Nana76 [90]
3 years ago
14

Finding the sum. imaginary numbers! hellpp

Mathematics
1 answer:
Neko [114]3 years ago
3 0
The "i" in this problem actually doesn't represent imaginary numbers. This is a summation problem which is asking for the sum of (2i+1) for when i = 1 to i = 7.

So (2(1) + 1) + (2(2) + 1) + (2(3) + 1) + (2(4) + 1)... etc...

The summation rules we need to know for this problem are for constants and for a single variable.

When we have a constant, the summation rule is n*c where n is the number of times.

When we have a single variable, the summation rule is n(n+1)/2.

So applying the summation rules where n = 7:

2(7)(7+1)/2 + 1(7)

(7)(8) + 7 = 63

The answer to the summation is 63.
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A tip jar contains x one-dollar bills and y five- dollar bills. There are 42 bills in the jar, and the total value is $90.00. Ho
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Answer:

30 one-dollar bills and 12 five-dollar bills.

Step-by-step explanation:

Let x represent number of one-dollar bills and y represent number of five-dollar bills.

We have been given that a tip jar contains x one-dollar bills and y five- dollar bills. There are 42 bills in the jar. We can represent this information in an equation as:

x+y=42...(1)

x=42-y...(1)

We are also told that the total value of all bills is $90.00.  We can represent this information in an equation as:

1x+5y=90...(2)

Upon substituting equation (1) in equation (2), we will get:

42-y+5y=90

42+4y=90

42-42+4y=90-42

4y=48

\frac{4y}{4}=\frac{48}{4}

y=12

Therefore, there are 12 five-dollar bills in the tip jar.

Upon substituting y=12 in equation (1), we will get:

x=42-y\\\\x= 42-12\\\\x=30

Therefore, there are 30 one-dollar bills in the tip jar.

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