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lapo4ka [179]
3 years ago
8

2x + y -z=9 -x + 6y + 2z =- 17 5x + 7y +z = 4

Mathematics
1 answer:
Effectus [21]3 years ago
3 0

Answer:

Step-by-step explanation:

What is y?

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If n is a positive integer, how many 5-tuples of integers from 1 through n can be formed in which the elements of the 5-tuple ar
Oksana_A [137]

Answer:

n + 4 {n \choose 2} + 6 {n \choose 3} + 4 {n \choose 4} + {n \choose 5}

Step-by-step explanation:

Lets divide it in cases, then sum everything

Case (1): All 5 numbers are different

 In this case, the problem is reduced to count the number of subsets of cardinality 5 from a set of cardinality n. The order doesnt matter because once we have two different sets, we can order them descendently, and we obtain two different 5-tuples in decreasing order.

The total cardinality of this case therefore is the Combinatorial number of n with 5, in other words, the total amount of possibilities to pick 5 elements from a set of n.

{n \choose 5 } = \frac{n!}{5!(n-5)!}

Case (2): 4 numbers are different

We start this case similarly to the previous one, we count how many subsets of 4 elements we can form from a set of n elements. The answer is the combinatorial number of n with 4 {n \choose 4} .

We still have to localize the other element, that forcibly, is one of the four chosen. Therefore, the total amount of possibilities for this case is multiplied by those 4 options.

The total cardinality of this case is 4 * {n \choose 4} .

Case (3): 3 numbers are different

As we did before, we pick 3 elements from a set of n. The amount of possibilities is {n \choose 3} .

Then, we need to define the other 2 numbers. They can be the same number, in which case we have 3 possibilities, or they can be 2 different ones, in which case we have {3 \choose 2 } = 3  possibilities. Therefore, we have a total of 6 possibilities to define the other 2 numbers. That multiplies by 6 the total of cases for this part, giving a total of 6 * {n \choose 3}

Case (4): 2 numbers are different

We pick 2 numbers from a set of n, with a total of {n \choose 2}  possibilities. We have 4 options to define the other 3 numbers, they can all three of them be equal to the biggest number, there can be 2 equal to the biggest number and 1 to the smallest one, there can be 1 equal to the biggest number and 2 to the smallest one, and they can all three of them be equal to the smallest number.

The total amount of possibilities for this case is

4 * {n \choose 2}

Case (5): All numbers are the same

This is easy, he have as many possibilities as numbers the set has. In other words, n

Conclussion

By summing over all 5 cases, the total amount of possibilities to form 5-tuples of integers from 1 through n is

n + 4 {n \choose 2} + 6 {n \choose 3} + 4 {n \choose 4} + {n \choose 5}

I hope that works for you!

4 0
3 years ago
Keith ate 2/6 of candy bar. If there were 6 pieces total, what fraction of the candy bar is left?
IgorC [24]
If there were 6 pieces and Keith ate 2 of the pieces, then there would be 4 pieces left.
\frac{4}{6}
and when you reduce it it would be 
\frac{2}{3}
5 0
2 years ago
Read 2 more answers
A map has a scale of 3 cm and 20 cm which statement is true or false two cities are actually 66 cm part are9.9 cm part
victus00 [196]
Answer:
Answer options
A. Two cities that are 7.5 cm apart on the map are actually 50 km apart.
D. Two cities that are actually 66 km apart are 9.9 cm apart on the map.
Step-by-step explanation:
Step 1
Indicate the scale as shown;
3 cm : 20 km, meaning 3 cm on the map represents 20 km on the ground
A). what does 7.5 cm represent on the ground
Distance on ground=(7.5×20)/3=50 km
B). what does 4 cm represent on the ground
Distance on ground=(4×20)/3=26.67 km
C). what does 45 km on ground represent on the map
Distance on map=(45×3)/20=6.75 cm
D). what does 66 km on ground represent on the map
Distance on the map=(66×3)/20=9.9 cm
8 0
2 years ago
I need help solving this pls
Oksana_A [137]

Answer:

Adding them together. x = 3/2, y = 8

Step-by-step explanation:

Adding because we want to get rid of a variable. If we add, 2x + 6x = 8x, 1/2 * y + (-1/2 * y) = 0, and 7 + 5 = 12. Adding gets rid of the y variable.

By adding we get that 8x = 12 which gives us x = 12/8 = 3/2

Substituting this back into either equation will give us y = 8.

8 0
2 years ago
What number increased by 75% is 35
Ne4ueva [31]

To solve this, you would do:

x + 75% * x = 35

7/4 * x = 35

x = 20

8 0
2 years ago
Read 2 more answers
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