True or false:

a. A product of two self-adjoint matrices is self-adjoint.
b. If A is self-adjoint, then Ak is self-adjoint.

Justify your conclusions

Answers

Answer 1

Answer:

Option a is "False".

Option b is "True".

Step-by-step explanation:

In point a:

Prove AB=BA

[tex]A=\left[\begin{array}{cc}1&2\\4&5\end{array}\right] \\\\B= \left[\begin{array}{cc}2&1\\8&5\end{array}\right][/tex]

Solve L.H.S part:

[tex]AB= \left[\begin{array}{cc}1&2\\4&5\end{array}\right] \times \left[\begin{array}{cc}2&1\\8&5\end{array}\right][/tex]

      [tex]= \left[\begin{array}{cc}2+16 &1+10\\8+40&4+25\end{array}\right]\\\\\\= \left[\begin{array}{cc}18 &11\\48&29\end{array}\right][/tex]

Solve R.H.S part:

[tex]BA= \left[\begin{array}{cc}2&1\\8&5\end{array}\right] \times \left[\begin{array}{cc}1&2\\4&5\end{array}\right][/tex]

      [tex]= \left[\begin{array}{cc}2+4 &4+5\\8+20&16+25\end{array}\right]\\ \\ \\= \left[\begin{array}{cc}6 &9\\28&41\end{array}\right][/tex]

So, [tex]AB \neq BA[/tex]

In point b:

[tex]A^{*} =A\\\\(Ak)^{*} =A^k[/tex]

if [tex]k= 1[/tex]it holds the trivially [tex]A^{*}=A ...........(1)[/tex]

by assuming that if it is true for [tex]k=n-1[/tex]

that is

[tex](A^{n-1})^{*}= A^{n-1}............(2) \\\\ if \ k=n\\\\\to (A^{n})^{*} = (A^{n-1} \cdot A^1)^{*} = A^{*}(A^{n-1})^{*} \\\\\to A(A)^{n-1}[/tex] use above equations

[tex]\to A^{n-1+1} \\\\ \to A^{n}[/tex]

that's why it is true.


Related Questions

PLEAS HELP ME!!!!!!!!!!!!!!!!Use a unit rate to find the unknown value.
52/13, 12/?

Answers

Answer:

1. 40/8 = 45/9

2. 42/14 = 15/5

3. 14/2 = 56/8

4. 8/4 = 26/13

Step-by-step explanation:

Find the ratio :
1/2 hour to 45 minutes​

Answers

Answer:

The answer is 2 : 3.

Step-by-step explanation:

First, you have to convert the units to minutes :

1 hr = 60 min

1/2 hr = 60 × 1/2 = 30 min

Then, you have to simplify the ratio to simplest form :

30 : 45

= (30÷15) : (45÷15)

= 2 : 3

Answer:

To see the ratio, we should have both in the same unit. We can pass 1/2 hour to minutes, as we know one hour are 60 minutes:

60/2 = 30

So we know half hour are 30 minutes.

Now, we know the ratio 30:45, but we can simplify it, as a fraction.

To simplify it, we will divide both numbers by the same quantity, in this case, divide 30 and 45 by 15 (a it's a divisor):

30/15 = 2 and 45/15 = 3, so the ratio is 30:45, which is equivalent to 2:3

Write as quotient of powers.

Answers

Answer:

I said C on my test but I'm pretty sure its right

which is the galaxy is the closest to our galaxy at the moment ​

Answers

Andromeda galaxy is your answer

I need help with this question.

Answers

Answer:

False.

Step-by-step explanation:

Any straight line may have infinite number of points (solutions) lying on it.

Therefor, straight line 'l' can't have exactly two solutions.

Line 'l' will have infinitely many solutions.

Exactly one or two solutions are possible only when two lines or functions intersect each other.

Therefore, answer is false.

Carla packed this box with 1-centimeter cubes. What is the volume of the box?

Answers

Answer:

60 cm 2

Step-by-step explanation:

Answer:

60 cubic cm

Step-by-step explanation:

i just multiplied 3 x 4 x 5 and that gave me 60 and cubic cm

hoped it helped :)

Please help thank you..

Solve the following equation:
3x^2= -12

Picture above of the options.^

Answers

Answer:

Step-by-step explanation:

option d

If 3x + 2y = 10 and 2x + 3y = 15, find the value
of x+y.​

Answers

Answer:

x+y=5

Step-by-step explanation:

Isolate y in the first equation:

3x+ 2y = 10

2y = 10 - 3x

y= (10 - 3x)/2

substitute this value of y into the second equation:

2x + 3 ((10 - 3x)/2) = 15

now solve for x:

2x + 3/2 (10 - 3x) =15

2x + 15 - 9/2x = 15

-5/2 x = 15 - 15

-5/2 x / (-5/2) = 0/(-5/2)

x=0

now use this value to solve for y:

y = (10 - 3(0))/2

y = 10/2

y = 5

now x+y

0+5=5

Believe it or not, there are some people who don't think that Duke will win the NCAA tournament this year. Let's say that you want to measure the average intelligence of Duke Doubters. Problem is you could only find 28 DDs on this whole campus. The mean of your sample was 90 and the standard deviation was 60. Calculate the 90% Confidence Interval for the IQ of DDs

Answers

Answer:

The 90% confidence interval is   [tex] 87.95   <  \mu < 92.05  [/tex]

Step-by-step explanation:

From the question we are told that

   The sample size is  [tex]n = 28[/tex]

    The  sample mean is  [tex]\= x = 90[/tex]

    The standard deviation is  [tex]s= 60[/tex]

Generally given that the sample size is not large enough i.e  n <  28 then we will make use of the t distribution table  

Generally the degree of freedom is mathematically represented as

         [tex]df = n- 1[/tex]    

=>      [tex]df = 28 - 1[/tex]  

=>      [tex]df = 2 7[/tex]

From the question we are told the confidence level is  95% , hence the level of significance is    

      [tex]\alpha = (100 - 95 ) \%[/tex]

=>   [tex]\alpha = 0.10[/tex]

Generally from the student t  distribution table the critical value  of  [tex]\frac{\alpha }{2}[/tex] at a degree of freedom of [tex]df = 2 7[/tex]  is  

   [tex]t_{\frac{\alpha }{2} , 27  } =  2.052[/tex]

Generally 95% confidence interval is mathematically represented as  

      [tex]\= x -E <  \mu <  \=x  +E[/tex]

=> [tex]90  - 2.052  <  \mu < 90  + 2.052  [/tex]

=> [tex] 87.95   <  \mu < 92.05  [/tex]

(x - 12) - 5 = 3x - 2

x = ?

Answers

Answer:

not equal

Step-by-step explanation:

Answer:

x= -7.5

Step-by-step explanation:

x-12-5=3x-2

x-17=3x-2

-2x=15

x=-7.5

Complete this division sentence.
9988 + 23 =
R

Answers

Correct question is;

Complete this division sentence.

9988 ÷ 23 = R

Answer:

9988 ÷ 23 = 434 R 6

Step-by-step explanation:

....... 434

_________

23|9988

......92

¯¯¯¯¯¯¯¯¯¯¯

........ 788

.........69

¯¯¯¯¯¯¯¯¯¯

........... 98

............92

¯¯¯¯¯¯¯¯¯¯¯

............. 6

Thus ; 9988 ÷ 23 = 434 R 6

What postulate/theorem can be used to prove the following triangles congruent?

Answers

Answer:

ASA

Step-by-step explanation:

since 2 angles and 1 side is the same, the triangles are congruent by the ASA theorem

Chris spending some of his birthday money on art supplies. He spends 1/6 of his money on paint and 2/3 of his money on markers. What fraction of his birthday money does he have left? (multi-step problem -must dd and subtract)
A. 5/6
B. 3/6
C. 1/2 (wrong)
D. 1/6

Answers

D - 1/6

Convert 2/3 into 4/6 add 1/6 to get 5/6 then subtract 6/6 by 5/6 to get 1/6

Please answer ASAP. Also please explain because even though I put it on here I still want to know how to do it. Tysmm

Answers

9514 1404 393

Answer:

  see below

Step-by-step explanation:

First row

Fill in the given x-value and solve for y:

  3(-4) +2y = -6

  -12 +2y = -6

  -6 +y = -3 . . . . . divide by 2

  y = 3 . . . . . . . . . add 6

__

Second row

Fill in the given y-value and solve for x:

  3x +2(0) = -6

  x = -2 . . . . . . . . . divide by 3

Which shows the equation below written in the form ax^2+bx+c=0 ? x^2+8x+10=3

Answers

Answer:

[tex]\boxed {\boxed {\sf x^2+8x+7=0}}[/tex]

Step-by-step explanation:

We want to put the equation into the standard form of a quadratic equation ([tex]ax^2+bx+c=0[/tex]). This allows us to factor or use the quadratic formula to find the roots.

We are given the equation:

[tex]x^2+8x+10=3[/tex]

We have to get a 0 on one side of the equation. The easiest way to do this is to "get rid" of the 3 on the right side using inverse operations.

It's a positive 3, so the inverse would be subtract. Subtract 3 from both sides of the equation.

[tex]x^2+8x+10-3=3-3[/tex]

[tex]x^2+8x+(10-3)=0[/tex]

[tex]x^2+8x+7=0[/tex]

The equation in standard form is x²+8x+7=0

Rewrite 8.24 × 10^6 in standard notation.

824,000
8,240,000,000
82,400,000
8,240,000

Answers

Answer:

The last choice 8,240,000.

Step-by-step explanation:

The exponent 6 tells us there are 6 digits after the first digit (8).

Answer is 8,240,000

I need some help please

Answers

Answer:

The awnser is A or -7/5

Step-by-step explanation:

you have to put the points into the formula y²-y¹/x²-x¹ (this is a fraction the y part is on top and the x part is on the bottom) then you need to plug in the numbers so it would look like 5-(-2)/-2-3. then you would add 5+2 since that is what -(-) means. then you would take 2+3 as -2-3. so the awnser would be -7/5.

Hope this helps

If you double the radius of a circle, then you will quadruple the circumference of the circle

Answers

Answer:

False

Step-by-step explanation:

No options is attached to the question. However, I'll assume it's a true or false question.

Represent the radius with r.

The circumference is calculated as:

X = 2πr

When the radius is doubled, the new radius R is

R = 2r

And the new circumference, C is:

C = 2πR

Substitute 2r for R

C = 2π * 2r

C = 4πr

Factorize the above equation.

C = 2 * 2πr

Recall X = 2πr;

The expression becomes:

C = 2 * X

C = 2X

This means that the circumference is doubled, not quadrupled.

Hence, the statement is false.

Let n1=50​, X1=10​, n2=50​, and X2=30. Complete parts​ (a) and​ (b) below. a. At the 0.10 level of​ significance, is there evidence of a significant difference between the two population​ proportions? Determine the null and alternative hypotheses. Choose the correct answer below. A. H0: π1≤π2 H1: π1>π2 B. H0: π1≠π2 H1: π1=π2 C. H0: π1≥π2 H1: π1<π2 D. H0: π1=π2 H1: π1≠π2 Your answer is correct. Calculate the test​ statistic, ZSTAT​, based on the difference p1−p2. The test​ statistic, ZSTAT​, is nothing.

Answers

Answer:

|Z| = |-4.089| > 1.645 at 0.10 level of significance

Null hypothesis is rejected at  0.10 level of significance

There is a difference between the two Population proportions

Step-by-step explanation:

Step(i):-

Given first sample size (n₁)  = 50

Given  proportion of the first sample p⁻₁= 0.2

Given second sample size (n₂)  = 50

Given proportion of the second sample p₂⁻ = 30/50 = 0.6

Null Hypothesis : H₀: p₁⁻=p₂⁻

Alternative Hypothesis : H₁: p₁⁻≠p₂⁻

Step(ii):-

Z-statistic

             [tex]Z = \frac{p_{1} -p_{2} }{\sqrt{pq(\frac{1}{n_{1} } +\frac{1}{n_{2}) } } }[/tex]

Where

         [tex]P = \frac{n_{1}p_{1} +n_{2} p_{2} }{n_{1} +n_{2} }[/tex]

        [tex]P = \frac{50X0.2+50X0.6}{50+50} = 0.4[/tex]

Z-statistic

       

      [tex]Z = \frac{0.2-0.6}{\sqrt{0.4 X 0.6(\frac{1}{50}+\frac{1}{50} } }[/tex]

     Z =  -4.089

Level of significance =0.10

Z₀.₁₀ = 1.645

|Z| = |-4.089| > 1.645 at 0.10 level of significance

Null hypothesis is rejected at  0.10 level of significance

Final answer:-

There is a difference between the two Population proportions

   

     

       

jimmy wants to buy socks that cost $20 how much change does he receive if he gives the cashier $100?

Answers

80 dollars is what jimmy would get back

find an equation in standard form of the parabola passing through the points (0, - 1), (1, 5), (- 1, - 5)

Answers

Answer:

The equation of the parabola in standard is [tex]y=x^{2}+5x-1[/tex]

Step-by-step explanation:

The standard form equation of the parabola is:

[tex]y=ax^{2}+bx+c[/tex]

Using the three points we can find a, b and c.

Let's put the first point (0,-1)into the standard form equation.

[tex]-1=a(0)^{2}+b(0)+c[/tex]

[tex]c=-1[/tex]

Using the second point (1,5) and the value of c found above.

[tex]5=a(1)^{2}+b(1)+c[/tex]

[tex]5=a+b-1[/tex]

[tex]6=a+b[/tex] (1)

Finally using the las point (-1,-5)  

[tex]-5=a(-1)^{2}+b(-1)+c[/tex]

[tex]-5=a-b-1[/tex]

[tex]-4=a-b[/tex] (2)  

Solving the system of equations (1) and (2) we can find a and b.

[tex]6=a+b[/tex]

[tex]-4=a-b[/tex]

Adding both of them we have:

[tex]2=2a[/tex]

[tex]a=1[/tex]

And b = 5.

Therefore, the equation of the parabola in standard form will be.

[tex]y=x^{2}+5x-1[/tex]

I hope it helps you!  

What is needed to prove the triangles are congruent?

Answers

Answer:

l ×b length ×breadth or h×b height ×breadth only this much or if you have other formula plz send me plz and what your name

Answer:

To prove triangles are congruent (equal) you must show that corresponding sides have the same measure as well as corresponding angles having the same number of degrees.

Step-by-step explanation:

Answer: You need to show that the measure of angle G is equal to the measure of angle T.

Write the equation of a parabola containing the point 6,3 with vertex at 5,-3

Answers

Answer:

y = 1/3 x 2 +4 x + 15

Step-by-step explanation:

y = a (x - h)2 + k

where (h,k) are the coordinates of the vertex and a is a multiplier

here (h,k) = ( - 6, 3)

y = a ( x + 6)2 + 3

to find a substitute (12,9) into the equation

9 = 18 a + 3

18 a = 9 - 3 = 6 a = 6/18 = 1/3

y = 1/3 (x + 6)2 + 3

distributing gives

y = 1/3 (x2 + 12x + 36) + 3

y = 1/3x2 + 4x + 15

Write the ratio as a fraction in simplest form, with whole numbers in the numerator and the denominator. 12 mi to 28 mi

Answers

Answer:

3/7

Step-by-step explanation:

12 ÷ 4

28 ÷ 4

Damian has two summer jobs. He works as a tutor, which pays $12 per hours, and he works as a lifeguard, which pays $9.50 per hour. He can work no more than 20 hours a week, but he wants to earn at least $220 per week. Which of the following systems of inequalities represents this situation, where x is the number of hours worked as a tutor, and y is the number of hours worked as a lifeguard?

A.12x + 9.5y ≤ 220 AND x + y ≥ 20
B.12x + 9.5y ≤ 220 AND x + y ≤ 20
C.12x + 9.5y ≥ 220 AND x + y ≤ 20
D.12x + 9.5y ≥ 220 AND x + y ≥ 20

Answers

Answer:

B 12x + 9.5y ≤ 220 AND x + y ≤ 20

Step-by-step explanation:

Answer:

A.12x + 9.5y ≤ 220 AND x + y ≥ 20

Step-by-step explanation:

≤ 220 symbolizes that he can earn 220 or more than 220.

≥ 20 symbolizes that he can work 20 hours or less.

What is the function written in vertex form?

f(x) = 4(x + 6)2 + 10
f(x) = 4(x + 6)2 – 26
f(x) = 4(x + 6)2 – 134
f(x) = 4(x + 6)2 + 154

Answers

4(x+6)2+10=8x+58
4(x+6)2-26=8x+22
4(x+6)2-134=8x-86
4(x+6)2+154=8x+202
~ I hope this helped!

Answer:

(C) f(x) = 4(x + 6)2 – 134

Step-by-step explanation:

edge 2022

A marketing researcher conducts a test to determine whether the number of chocolate chips per cookie differs significantly across two brands of chocolate chip cookies. A random sample of 10 Chewy Delight cookies reveals a mean of 6.4 chocolate chips per cookie and a standard deviation of 1.1 chocolate chips per cookie. A random sample of 11 Chips Destroy cookies reveals a mean of 5.6 chocolate chips per cookie and a standard deviation of 1.7 chocolate chips per cookie. Assuming unequal population variances, what is the calculated value for the associated test statistic?

Answers

Answer: the value for the associated test statistic is 1.2653

Step-by-step explanation:

Given that;

sample size one n₁ = 10

mean one x"₁ = 6.4

standard deviation one S₁ = 1.1

sample size two n₁ = 11

mean two x"₂ = 5.6

standard deviation one S₁ = 1.7

H₀ : μ₁ = μ₂

H₁ : μ₁ ≠ μ₂

Pooled Variance

sp = √( { [(n₁ - 1) × s₁² + (n₂ - 1) × s₂²] / (n₁ + n₂ - 2)} × (1/n₁ + 1/n₂))

we substitute

= √( { [(10 - 1) × (1.1)² + (11 - 1) × (1.7)²] / (10 + 11 - 2)} × (1/10 + 1/11))

= √( { [(9) × 1.21 + (10) × 2.89]  / (19) } × (0.1909))

= √({[ 39.79 ]  / 19} × (0.1909))  

= √( 2.0942 × 0.1909)

= √( 0.39978 )

= 0.63228

Now Test Statistics will be;

t = ( x"₁ - x"₂) / sp

we substitute

t = ( 6.4 - 5.6) / 0.63228

t = 0.8 / 0.63228

t = 1.2653

Therefore the value for the associated test statistic is 1.2653

124 – 70 = n – 35 I need the answer i please this is very importend

Answers

Answer:

N=89

59 = n - 35

54+35 = n

89=n

n=89

Which product is positive?

Answers

Answer:

The 3rd one

Step-by-step explanation:

Can have brainliest

Answer:

The 3rd one

Step-by-step explanation:

hope it helps

also can i have brainlist

divide partial quotient 308 divide by 4

Answers

Answer:

77 is the answer your welcome

77. Might be wrong so yeah
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