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STALIN [3.7K]
3 years ago
10

Prove that if BA=I then BA=AB.

Mathematics
1 answer:
Zanzabum3 years ago
4 0

Answer with Step-by-step explanation:

Since we have given that

BA=I

As we know that

AA⁻¹ = I (A is invertible matrix)

Multiplying A⁻¹ on the both the sides:

BAA^{-1}=IA^{-1}\\\\B=A^{-1}

Using the above result, we get that

BA=I=AA^{-1}\\\\BA=AB

Therefore, BA = AB

Hence, proved.

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Suppose that a college determines the following distribution for X = number of courses taken by a full-time student this semeste
lidiya [134]

Answer:

E(X) = \sum_{i=1}^n X_i P(X_i) = 3*0.07 +4*0.4 +5*0.25 +6*0.28= 4.74In order to find the variance we need to calculate first the second moment given by:

E(X^2) = \sum_{i=1}^n X^2_i P(X_i) = 3^2*0.07 +4^2*0.4 +5^2*0.25 +6^2*0.28= 23.36And the variance is given by:

Var(X) = E(X^2) +[E(X)]^2 = 23.36 -[4.74]^2 = 0.8924

And the deviation would be:

Sd(X) =\sqrt{0.8924} =0.9447

Step-by-step explanation:

Previous concepts

The expected value of a random variable X is the n-th moment about zero of a probability density function f(x) if X is continuous, or the weighted average for a discrete probability distribution, if X is discrete.

The variance of a random variable X represent the spread of the possible values of the variable. The variance of X is written as Var(X).  

Solution to the problem

For this case we have the following distribution given:

X          3      4       5        6

P(X)   0.07  0.4  0.25  0.28

We can calculate the mean with the following formula:

E(X) = \sum_{i=1}^n X_i P(X_i) = 3*0.07 +4*0.4 +5*0.25 +6*0.28= 4.74

In order to find the variance we need to calculate first the second moment given by:

E(X^2) = \sum_{i=1}^n X^2_i P(X_i) = 3^2*0.07 +4^2*0.4 +5^2*0.25 +6^2*0.28= 23.36

And the variance is given by:

Var(X) = E(X^2) +[E(X)]^2 = 23.36 -[4.74]^2 = 0.8924

And the deviation would be:

Sd(X) =\sqrt{0.8924} =0.9447

3 0
3 years ago
What is the area of the parallelogram shown below in square units? 9 units 20 units
tatyana61 [14]

Answer

160

Step-by-step explanation:

3 0
3 years ago
Read 2 more answers
Which two angles are congruent
Anna35 [415]
Angles FED and angle JKL
5 0
3 years ago
What is the factored form of 2x2 + x-3?
Vesnalui [34]

Answer:

Step-by-step explanation:

a = 2, b = 1, c = -3

We need to factor this by finding the product of a and c, then from there find which factors of a * c will either add or subtract to give us b.

a * c = 6  and the factors of 6 and 1 and 6, 2 and 3.  Well, 6 - 1 doesn't equal 1 and neither does 6 + 1.  So our factors are 3 and 2.  In order to combine those to get a 1 (our b), we will subtract 2 from 3 since 3 - 2 = 1.  That means that 3 is positive and 2 is negative.  Filling in the formula with 3 and 2 in place of 1 looks like this (always remember to put the absolute value of the largest number first):

2x^2+3x-2x-3=0

Group the first 2 terms together and the second 2 term together in order to factor:

(2x^2+3x)-(2x-3)=0 and factor out what's common in each set of parenthesis.

x(2x+3)-1(2x+3)=0

Notice that when we factor out a -1 from the second set of parenthesis, we can distribute it back in to get the equation we started with.  We know that factoring by grouping "works" if what is inside both sets of parenthesis is exactly the same.  Ours are identical: (2x + 3).  That is common now, and can be factored out:

(2x+3)(x-1)=0

That matches your first choice

6 0
3 years ago
In the first 3 days of class, Maria lost 2 pencils. If maria keeps losing pencils at the same rate for 60 days of class, how man
Lyrx [107]
Rounded to the nearest whole number, it seems as if she will lose 40 pencils at this rate.

2/3 = .66
60x.66=39.6
39.6 - 40

Hope this was helpful!
6 0
3 years ago
Read 2 more answers
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