Ask question

Ask question

All categories

3 years ago

9

A homogeneous second-order linear differential equation, two functions y1 and y2 , and a pair of initial conditions are given be

low. First verify that y1 and y2 are solutions of the differential equation. Then find a particular solution of the form
y = c1y1 + c2y2 that satisfies the given initial conditions.
y'' + 49y = 0; y1 = cos(7x) y2 = sin(7x); y(0) = 10 y(0)=-4
y(x)=?

1 answer:

Basile [38]3 years ago

4 0

Answer:

Step-by-step explanation:

Check part

$y= C_1y_1 + C_2y_2 = C_1cos(7x)+C_2sin(7x)$

$y'= -7 C_1sin(7x)+7C_2cos(7x)$

$y"= -49 C_1cos(7x) - 49 C_2sin(7x)$

Now, replace to the original one.

$y"+49 y = -49C_1cos(7x)-49 C_2 sin(7x) + 49 C_1cos(7x) +49 C_2sin(7x) = 0\\$

Done!!

Particular solution

$y(0) = C_1cos(0) + C_2 sin(0) = C_1= 10$

I believe that y'(0) = 4, not y(0) anymore. Since y(0) CANNOT have two different solution.

$y(0)'= -7 C_1sin(0) + 7 C_2 cos (0) = 7 C_2= -4$

$C_2 = -4/7$

The last step is to put C1, C2 into your solution. You finish it.

You might be interested in

Can someone please help I can’t understanddd.

dem82 [27]

Hello,

Dividing by 0 is not defined so let s take x different from 4 and -4 and then we can write:

As

$f(x)=x^2-7x+12=x^2-4x-3x+12=x(x-4)-3(x-4)=(x-4)(x-3)\\ \\(f\times g)(x)=\dfrac{3(x-4)(x-3)}{(x-4)(x+4)}=\dfrac{3x-9}{x+4}$

Thanks

6 0

3 years ago

Find the value of x. 6 8 4 x

snow_tiger [21]

Answer:

3

Explanation:

4 is half of 8 on the right side, so that means X has to be half of 6, so it’s 3. Also, it couldn’t be 2 because it is too big, and it can’t be 4 because it isn’t the same length as the other 4, so it’s 3

8 0

3 years ago

Anarel [89]

Answer:

the trainee calculated the incorrect amount

It should be 0.5 mL

Step-by-step explanation:

The physician orders penicillin 500,000 units for a patient while the concentration of the drug you have is 1,000,000 units/ 1mL. It's clear that 1mL drug is too much for the patient since 1,000,000 units are higher than 500,000 units.

The amount of penicillin in 1.5 mL will be definitely higher than 1,000,000 units, so it must be a lot higher than the physician's orders. We can roughly guess that the trainee draws an incorrect amount.

To calculate the exact volume you need, you have to divide the amount of the drug you need with the concentration of the drug. The calculation will be:

the volume needed = amount of the drug you need/ concentration of the drug

volume needed = 500,000 units / (1,000,000 units/ 1mL)= 1/2 mL = 0.5 mL

8 0

3 years ago

Write a subtraction fact with the same difference as 16 -7

hoa [83]

14-5=9, 12-3=9, 15-6=9

7 0

3 years ago

Read 2 more answers

It is estimated that 75% of all young adults between the ages of 18-35 do not have a landline in their homes and only use a cell

Mademuasel [1]

Answer:

a) 75

b) 4.33

c) 0.75

d) $3.2 \times 10^{-13}$ probability that no one in a simple random sample of 100 young adults owns a landline

e) $6.2 \times 10^{-61}$ probability that everyone in a simple random sample of 100 young adults owns a landline.

f) Binomial, with $n = 100, p = 0.75$

g) $4.5 \times 10^{-8}$ probability that exactly half the young adults in a simple random sample of 100 do not own a landline.

Step-by-step explanation:

For each young adult, there are only two possible outcomes. Either they do not own a landline, or they do. The probability of an young adult not having a landline is independent of any other adult, which means that the binomial probability distribution is used to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

75% of all young adults between the ages of 18-35 do not have a landline in their homes and only use a cell phone at home.

This means that $p = 0.75$

(a) On average, how many young adults do not own a landline in a random sample of 100?

Sample of 100, so $n = 100$

$E(X) = np = 100(0.75) = 75$

(b) What is the standard deviation of probability of young adults who do not own a landline in a simple random sample of 100?

$\sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{100(0.75)(0.25)} = 4.33$

(c) What is the proportion of young adults who do not own a landline?

The estimation, of 75% = 0.75.

(d) What is the probability that no one in a simple random sample of 100 young adults owns a landline?

This is P(X = 100), that is, all do not own. So

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 100) = C_{100,100}.(0.75)^{100}.(0.25)^{0} = 3.2 \times 10^{-13}$

$3.2 \times 10^{-13}$ probability that no one in a simple random sample of 100 young adults owns a landline.

(e) What is the probability that everyone in a simple random sample of 100 young adults owns a landline?

This is P(X = 0), that is, all own. So

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 0) = C_{100,0}.(0.75)^{0}.(0.25)^{100} = 6.2 \times 10^{-61}$

$6.2 \times 10^{-61}$ probability that everyone in a simple random sample of 100 young adults owns a landline.

(f) What is the distribution of the number of young adults in a sample of 100 who do not own a landline?

Binomial, with $n = 100, p = 0.75$

(g) What is the probability that exactly half the young adults in a simple random sample of 100 do not own a landline?

This is P(X = 50). So

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 50) = C_{100,50}.(0.75)^{50}.(0.25)^{50} = 4.5 \times 10^{-8}$

$4.5 \times 10^{-8}$ probability that exactly half the young adults in a simple random sample of 100 do not own a landline.

8 0

2 years ago