Is 9.4 rational or irrational :p, please help

Rewrite f(x)=2(2-1)^2+3 from vertex form to standard

Ostrovityanka [42]

F(x)=3^2+3
F(x)=6+3
F(x)=9

6 0

3 years ago

For the matrices below. Find all (real) eigenvalues. <br><br> A= [7 9]<br> [0 9]

Jet001 [13]

Answer:

The answer is "9 and 7".

Step-by-step explanation:

Given:

$A=\left[\begin{array}{cc}7&9\\0&9\end{array}\right]$

Using formula:

$|A-\lambda \cdot I|= 0\\\\$

$\to |\left[\begin{array}{cc}7&9\\0&9\end{array}\right]-\lambda \left[\begin{array}{cc}1&0\\0&1\end{array}\right] |=0\\\\\\ \to |\left[\begin{array}{cc}7&9\\0&9\end{array}\right]- \left[\begin{array}{cc}\lambda&0\\0&\lambda\end{array}\right] |=0\\\\\\\to|\left[\begin{array}{cc}7-\lambda &9\\0&9-\lambda\end{array}\right]|=0\\\\\\\to|(7-\lambda)(9-\lambda)|=0\\\\\to (7-\lambda)(9-\lambda)=0\\\\\to 7-\lambda=0 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 9-\lambda=0\\\\$

$\to \lambda=7 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \lambda=9\\\\$

8 0

2 years ago

3. Miss. Mead pays Miss. Adams $160.00 per week. She works 40 hours per week. Miss. Adams

Leno4ka [110]

Answer:

B. $18.00

Step-by-step explanation

160/4 divide 160 by 4 to see how much Miss Adams makes and hour

She makes $4 an hour

multiply this ($4) by her idle time (4.5) hours to get $18

8 0

2 years ago

I need help please. Thanks!

Karolina [17]

Answer:

A

Step-by-step explanation:

We are given the function f and its derivative, given by:

$f^\prime(x)=x^2-a^2=(x-a)(x+a)$

Remember that f(x) is decreasing when f'(x) < 0.

And f(x) is increasing when f'(x) > 0.

Firstly, determining our zeros for f'(x), we see that:

$0=(x-a)(x+a)\Rightarrow x=a, -a$

Since a is a (non-zero) positive constant, -a is negative.

We can create the following number line:

<-----(-a)-----0-----(a)----->

Next, we will test values to the left of -a by using (-a - 1). So:

$f^\prime(-a-1)=(-a-1-a)(-a-1+a)=(-2a-1)(-1)=2a+1$

Since a is a positive constant, (2a + 1) will be positive as well.

So, since f'(x) > 0 for x < -a, f(x) increases for all x < -a.

To test values between -a and a, we can use 0. Hence:

$f^\prime(0)=(0-a)(0+a)=-a^2$

This will always be negative.

So, since f'(x) < 0 for -a < x < a, f(x) decreases for all -a < x < a.

Lasting, we can test all values greater than a by using (a + 1). So:

$f^\prime(a+1)=(a+1-a)(a+1+a)=(1)(2a+1)=2a+1$

Again, since a > 0, (2a + 1) will always be positive.

So, since f'(x) > 0 for x > a, f(x) increases for all x > a.

The answer choices ask for the domain for which f(x) is decreasing.

f(x) is decreasing for -a < x < a since f'(x) < 0 for -a < x < a.

So, the correct answer is A.

3 0

2 years ago

A survey found that women's heights are normally distributed with mean 63.7 . And standard deviation 3.7 . The survey also foun

san4es73 [151]

Complete question :

A survey found that women's heights are normally distributed with mean 63.6 in and standard deviation 3.7 in. The survey also found that men's heights are normally distributed with mean 69.3 in and standard deviation 3.7 in. Consider an executive jet that seats six with a doorway height of 55.7 in.

1-What percentage of adult men can fit through the door without bending?

2-) Does the door design with a height of 56.35in. appear to be adequate? Why didn't the engineers design a larger door? Choose answer below

A. The door design is inadequate, because every person needs to be able to get into the aircraft without bending. There is no reason why this should not be implemented.

B. The door design is adequate, because the majority of people will be able to fit without bending. Thus, a larger door is not needed.

C. The door design is inadequate, but because the jet is relatively small and seats only six people, a much higher door would require major changes in the design and cost of the jet, making a larger height not practical.

D. The door design is adequate, because although many men will not be able to fit without bending, most women will be able to fit without bending. Thus, a larger door is not needed.

Answer:

A.) 0.135%

B.) C. The door design is inadequate, but because the jet is relatively small and seats only six people, a much higher door would require major changes in the design and cost of the jet, making a larger height not practical.

C.)

Step-by-step explanation:

Percentage of adult men that can fit the door without bending :

Obtain the Zscore :

Mean height of men, m = 67.5

Standard deviation, s = 3.7

Zscore = (x - m) / s ; where x = 56.4

Zscore = (56.4 - 67.5) / 3.7

Zscore = - 11.1 / 3.7

Zscore = - 3

P(Z < - 3) = 0.0013499 (Z probability calculator)

P(Z < - 3) = 0.0013499 * 100% = 0.13499%

8 0

2 years ago