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vagabundo [1.1K]
2 years ago
7

Help finding the sum

Mathematics
1 answer:
Mamont248 [21]2 years ago
5 0
It is asking you to find the sum of k^2 - 1 from k=1 to k=4. Since that is only 4 numbers, calculating the sum by hand wouldn’t be that bad.

(1^2 - 1) + (2^2 - 1) + (3^2 - 1) + (4^2 - 1) = 26

The easier way to find the sum is to use a few simple formulas.

When we have a term that is just a constant c, the formula is c*n.

When we have a variable k, the formula is k*n*(n+1)/2.

When we have a squared variable, the formula is k*n*(n+1)*(2n+1)/6.

In this case, we have a squared variable k^2 and a constant of -1.

So plug in n=4 to the formulas:

4*5*9/6 - 1*4 = 26

The answer is 26







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Joshua earned $60 for working h hours. Which expression represents how much he earned in 1 hour?
Shkiper50 [21]
D. 60 divided by h.

Hope this helped.
5 0
3 years ago
Read 2 more answers
The work of a student to solve the equation 2(5y − 2) = 12 + 6y is shown below:
jolli1 [7]
We know that Step 1 is correct, because it is just a restatement of the equation. Therefore, we can eliminate Step 1:

2(5y – 2) = 12 + 6y

In Step 2, the student tried using the Distributive Property. The Distributive Property can be written as one of the two following formulas:

a(b + c) = ab + ac
a(b – c) = ab – ac

In this case, we'll use the second formula. Substitute any known values into the equation above and simplify:

2(5y – 2) = 2(5y) – 2(2)
2(5y – 2) = 10y – 4

In Step 2, the student calculated 2(5y – 2) to equal 7y – 4. However, we have just proven that 2(5y – 2) is equal to 10y – 4.

The student first made an error in Step 2, and the correct step is:

Step 2: 10y – 4 = 12 + 6y

I hope this helps!
8 0
3 years ago
A bakery the price of the cake is nine dollars more than the price of a pie. One day the bakery sold 8 cakes and 14 pies for a t
gavmur [86]

Answer:

The price of the cake is $24 and the price of the Pie is $15

Step-by-step explanation:

Given

<em>Represent price of Cake with C and Price of Pie with P</em>

C = 9 + P

Cakes sold = 8

Pies sold = 14

Total = \$402

Required

Determine C and P

To represent the cakes and pies sold, we have the following expression

8C + 14P = 402

Substitute 9 + P for C

8(9+P) + 14P = 402

Open the bracket

72 + 8P + 14P = 402

Collect Like Terms

8P + 14P = 402 - 72

22P= 330

Divide both sides by 22

P = \frac{330}{22}

P = 15

Recall that

C = 9 + P

C = 9 + 15

C = 24

<em>Hence, the price of the cake is $24 and the price of the Pie is $15</em>

7 0
3 years ago
I need help with number 3 .
djverab [1.8K]

Answer:

there are 6 activities therefore 360/6 = 60 minutes on each activity

Step-by-step explanation:

5 0
3 years ago
Hey! i’ll give brainliest please help.
dexar [7]

The last name I am pretty sure of it.

7 0
3 years ago
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