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Maru [420]
3 years ago
8

How many combinations of 7 candidates can fill 3 vacancies on a city council?

Mathematics
1 answer:
yKpoI14uk [10]3 years ago
8 0

Answer:

35 combinations

Step-by-step explanation:

You have to use the formula for finding combinations in probability.  It looks like this:

₇C₃ = \frac{7!}{3!(7-3)!}

so that gives you

₇C₃ = \frac{7*6*5*4!}{3*2*1*4!}

The 4 factorials cancel each other out, and when you do the math, you get 210/6.  That divides evenly into 35.  So there are 35 combinations.

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Let M be the set of all nxn matrices. Define a relation on won M by A B there exists an invertible matrix P such that A = P BP S
Sophie [7]

Answer:

Recall that a relation is an <em>equivalence relation</em> if and only if is symmetric, reflexive and transitive. In order to simplify the notation we will use A↔B when A is in relation with B.

<em>Reflexive: </em>We need to prove that A↔A. Let us write J for the identity matrix and recall that J is invertible. Notice that A=J^{-1}AJ. Thus, A↔A.

<em>Symmetric</em>: We need to prove that A↔B implies B↔A. As A↔B there exists an invertible matrix P such that A=P^{-1}BP. In this equality we can perform a right multiplication by P^{-1} and obtain AP^{-1} =P^{-1}B. Then, in the obtained equality we perform a left multiplication by P and get PAP^{-1} =B. If we write Q=P^{-1} and Q^{-1} = P we have B = Q^{-1}AQ. Thus, B↔A.

<em>Transitive</em>: We need to prove that A↔B and B↔C implies A↔C. From the fact A↔B we have A=P^{-1}BP and from B↔C we have B=Q^{-1}CQ. Now, if we substitute the last equality into the first one we get

A=P^{-1}Q^{-1}CQP = (P^{-1}Q^{-1})C(QP).

Recall that if P and Q are invertible, then QP is invertible and (QP)^{-1}=P^{-1}Q^{-1}. So, if we denote R=QP we obtained that

A=R^{-1}CR. Hence, A↔C.

Therefore, the relation is an <em>equivalence relation</em>.

4 0
3 years ago
Ify is 6 when x is 3 and y varies directly with x, find y when x is 8.
Contact [7]
Y would be 16,

y=kx
6=3k
2=k
y=2(8)
y=16
4 0
3 years ago
I'm Mrs.Moores class, the ratio of boys to girls is 4:6. If there are 30 students in the class, how many girls are in class?
liubo4ka [24]

Answer:

24

Step-by-step explanation:

6×5=30

6*4=24

you have to find more then half which would be 3:6 so it's more then 15 but less then 30

5 0
3 years ago
A lasagna recipe uses 1 2/4 teaspoon basil 1/4 teaspoon pepper and 4 teaspoons parsley if you double the recipe how many teaspoo
Nimfa-mama [501]

Answer:

11 1/2 teaspoons

Step-by-step explanation:

1 2/4 basil= 1.5 tsp If you multiply this by two to double the recipe you will have 3 teaspoons of basil.

1/4*2= 2/4 pepper

4*2=8 parsley

After you double everything you need to add them together:

3+2/4+8

Which brings you to the final answer of 11 2/4 teaspoons or if you simplify it.... 11 1/2 teaspoons

6 0
3 years ago
A set of numbers is shown below:
bonufazy [111]
You can go through the set and test each one out:
x=0:
2(0)+3 ≥ 7?     Or 3≥7? No

x=0.6:
2(0.6)+3≥7?     4.2≥7? No.

x=2:
2(2)+3≥7?     7≥7? Yes.

x=4:
2(4)+3≥7?     11≥7? Yes.

x=6:
2(6)+3≥7?     15≥7? Yes.

The set is {2, 4, 6}.
8 0
3 years ago
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