# Posts by Francesca

Total # Posts: 157

**maths**

on an island without squirrels some squirrels are introduced. a mathematical model of the population growth of squirrels on the island is given by the function f defined by f(x)= 1320/(1 + e^(5,1-0.66x)) where x is the time in years after the introduction a)how many squirrels ...

**Science**

Thank you!

**Science**

What is water treatment? Is it also the same with water filtration? Please answer! Thanks

**Physics**

A baseball is hit off the edge of a cliff horizontally at a speed of 30 m/s. It takes the ball 3 seconds to reach the ground, with no air resistance. How high is the cliff wall?

**chemistry**

Calculate the pH for each of the following cases in the titration of 50.0 mL of 0.150 M HClO(aq) with 0.150 M KOH(aq). The ionization constant for HClO is 4.0x10^-8. pH before the addition of any KOH? pH after the addition of 25 mL of KOH? Please show the steps to solving this...

**CHemistry**

Calculate the pH at the equivalence point for the titration of 0.140 M methylamine (CH3NH2) with 0.140 M HCl. The Kb of methylamine is 5.0× 10–4.

**Chemistry**

Calculate the morality of a solution that contains a 4.0 mol of a solute dissolved in 12.0L of solution

**Finance**

Also, how would you calculate the IRR? Thank you for any help!

**Finance**

An income-producing property is priced at $600,000 and is expected to generatethe following after-tax cash flows: Year 1: $42,000; Year 2: $44,000; Year 3:$45,000; Year 4: $50,000; and Year 5: $650,000. Would an investor with arequired after-tax rate of return of 15 percent be...

**Math**

what is 18 percent of 240?

**Math**

it is a

**Physics**

The given are (a) the speed of sound, which is 395 m/s, (b) the velocity of the moving source, which is 12 m/s, and (c) the frequency of the sound both cars are emitting, which is 395 Hz. Let's assume that f{o} is the frequency the observer can hear and f{s} is the ...

**Accounting**

Sierra Company is considering a long-term investment project called ZIP. ZIP will require an investment of $121,200. It will have a useful life of 4 years and no salvage value. Annual revenues would increase by $79,180, and annual expenses (excluding depreciation) would ...

**Business Finance**

Neville Corporation, an amusement park, is considering a capital investment in a new exhibit. The exhibit would cost $174,777 and have an estimated useful life of 9 years. It will be sold for $69,200 at that time. (Amusement parks need to rotate exhibits to keep people ...

**Math**

Thank you!

**Math**

how do you solve: 4=1(2)/(x-2) Thank you!

**Math**

1.) Find the producers' surplus if the supply function is: S(q) = q^7/2+3q^5/2 + 54. Assume the supply and demand are in equilibrium at q= 25. 2.) S(q) = q^2 + 12q and D(q) = 900 - 18q - q^2 The point at which the supply and demand are equilibrium is (15, 405). a.) Find ...

**Math**

1.) Find the producers' surplus if the supply function is: S(q) = q^7/2+3q^5/2 + 54. Assume the supply and demand are in equilibrium at q= 25. 2.) S(q) = q^2 + 12q and D(q) = 900 - 18q - q^2 The point at which the supply and demand are equilibrium is (15, 405). a.) Find ...

**Math**

1.) Find the producers' surplus if the supply function is: S(q) = q^7/2+3q^5/2 + 54. Assume the supply and demand are in equilibrium at q= 25. 2.) S(q) = q^2 + 12q and D(q) = 900 - 18q - q^2 The point at which the supply and demand are equilibrium is (15, 405). a.) Find ...

**Math**

588 is the correct answer!**

**Math**

588 is the correct answer? But, I don't understand how to get to that number. How did you calculate that? Sorry, that may be a lot to type out

**Math**

Use the definite integral to find the area between the x-axis over the indicated interval. f(x) = 36 - x^2; [-1,13] So, what does be the area between the x-axis and f(x) equal? Thank you for any help! I'm really confused with this problem!

**Math**

Thank you!

**Math**

Solve for x. .006x^3=8889 x = approx 114, but I don't understand how to get that answer. Can anyone help me solve? Thank you!

**Math**

Thank you guys!

**Math**

Can someone please help me find the derivative of the following: y = (-9e^7x) / (5x+3) Thank you!

**chemistry**

Data given are related to the Born-Haber cycle for HCl Calculate the amount of energy lost when the ionic species return to their molecular form. Atomization of ½H2(g)=217.6KJ/mol 1st Ionisation of ½H2(g)=1312KJ/mol Atomization of ½Cl2(g)=121 KJ/mol 1st ...

**Accounting**

Any help?

**Accounting**

The balance sheet of Burger King reports current assets of $30,500 and current liabilities of $15,800. Calculate the current ratio of Burger King and detemine whether it will increase or decrease as a result of the following transactions: -Paid $2,030 cash for a new oven. &#...

**Math**

Find the value of x: 20x ≡ 9 (mod 15)

**Math**

Thanks for your help! Also, I am kind of confused about finding the value of x. Example: 9x ≡ 1 mod 10 How do I solve this?

**Math**

How do I solve for negative modular arithmetic? Here is an example: -45 mod 13 = 7, but how?

**Math**

How do I solve for negative modular arithmetic? Here is an example: -45 mod 13 = 7, but how?

**Ecology**

BYWEEE

**Computing in Security (Conversion Help)**

1.) Encrypt the hexadecimal message F9E8 using the Rail Fence cipher for binary numbers with 3 Rails. [Give answer in hexadecimal encrypted message] 2.) Decrypt the hexadecimal encrypted message CDEF created by the Rail Fence cipher for binary numbers with 3 Rails. [Give ...

**CIS**

Sorry it's computing in security, so I guess that would fall under computers. . .

**CIS**

1.) Encrypt the hexadecimal message F9E8 using the Rail Fence cipher for binary numbers with 3 Rails. [Give answer in hexadecimal encrypted message] 2.) Decrypt the hexadecimal encrypted message CDEF created by the Rail Fence cipher for binary numbers with 3 Rails. [Give ...

**IP address assignment**

Yea I tried doing a google search, but nothing good explaining where to start. Thnx for the reply though

**IP address assignment**

Imagine that you are a system administrator for a company, and that the company operates from two locations Phoenix and Boston. Phoenix has 350 hosts and Boston has 2100. Given that the following class C IP addresses have been assigned to your company as a whole by ICANN: 220....

**Computing in Security (Conversion Help)**

1.) Express each decimal number as an 8-bit binary number in the 2's complement form and then find the negative of the representation of that number in two’s compliment a.) +18 b) -117 Thanks for any help!

**Thermal Physics**

Two cars collide head on while each is travelling at 80 km/hr. Suppose all of their kinetic energy is transformed into thermal energy. What is the temperature increase of each car? [You may assume that the specific heat capacity of each car is that of iron, 449 J kg-1K-1.]

**Physics of materials**

Gaseous nitrogen has a density of 1.17 kg/m3 and liquid nitrogen has a density of 810 kg/m3. [The relative molecular mass of nitrogen is 28.0] What is the mean volume per nitrogen molecule in each case? What is the mean separation between nitrogen molecules in each case?

**Discrete Math**

THANK YOU! :)

**Discrete Math**

A factory makes automobile parts. Each part has a code consisting of a letter and three digits, such as C117, O076, or Z920. Last week the factory made 60,000 parts. Prove that there are at least three parts that have the same serial number.

**Discrete Math**

isisDOTpolyDOTedu/courses/discretemath/problemsDOTpdf Link is above can you please take a look? Specifically #21 on pg. 345. [There are 900 3DN], I need help with g-h. Thank you.

**Discrete Math**

Can someone help? Very confused. . . John Sununus was once the governor of New Hampshire, and his name reminds one of the authors of a palindrome (a words which is spelt the same way forwards as backwards, such as SUNUNUS). How many seven-letter palindromes (not necessarily ...

**Discrete Math**

Basically for the MPD problem I have to make it more precise.

**Discrete Math**

Ok now I am confused again with 5:08, it seems the same as the first subpart of the problem. They can't be the same answer, for this one: How many seven-letter palindromes contain at most three different letters one of which is S? And for the MPD problem that was really ...

**Discrete Math**

Can you at all help with this? Multiple personality disorder (MPD) is a condition in which different personalities exist within one person and at various times control that person’s behavior. In a recent survey of people with MPD, it was reported that “98% had been ...

**Discrete Math**

Oh ok so there are 13800 that contain at most three different letters one of which is S.

**Discrete Math**

So, how many seven-letter palindromes contain at most three different letters one of which is S? We would start out with 26^3, but I don't understand how to make sure S will be included as one of the different letters. Any suggestions? Thank you.

**Discrete Math**

Oh okay I think I am following. . .

**Discrete Math**

To be honest I haven't started yet, but your method sounds like a step in the right direction. . .I'll play around with it for a little and see what I get. . .If you figure out anything post. Hopefully someone who knows something will post cuz I'm lost

**Discrete Math**

Any suggestions?

**Discrete Math**

Okay I continued the first problem: |A ∩ B| = [2000/6] = 333 |B ∩ C| = [2000/15] = 133 |C ∩ D| = [2000/35] = 57 |A ∩ D| = [2000/14] = 142 |A ∩ B ∩ C ∩ D| = [2000/210] = 9 1000 + 666 + 400 + 285 - 333 - 133 - 57 - 142 + 9 = 1695 <--...

**Discrete Math**

Is this correct? • Using the Principle of Inclusion-Exclusion, find the number of integers between 1 and 2000 (inclusive) that are divisible by at least one of 2, 3, 5, 7. A = {n| 1 ≤ n ≤ 2000, 2 |n} B = {n| 1 ≤ n ≤ 2000, 3 |n} C = {n| 1 ≤ n...

**Discrete Math**

Hey thanks a lot for help!

**Discrete Math**

Well a_1 = 37 not 31

**Discrete Math**

So, going back to the previous 9:05. The solution is a_n = 40(1)^n - 3(1)^n, is this correct or way off?

**Discrete Math**

How about this: Solve the recurrence relation a_n+1 = -8a_n – 16a_n - 1, n ≥ 1, given a₀ = 5, a₁ = 17. Characteristic polynomial is: x^2 + 8x + 16 with distinct roots -4. Since the roots are equal a0 = 5 = C1(-4)^0 + C2(0)(-4)^0 making C1 = 5, right? But...

**Discrete Math**

So the characteristic roots are 1?

**Discrete Math**

Idk what happened at 7:24 I think my computer had a glitch or something and it reposted. This one is throwing me for a loop: Solve the recurrence relation a_n = 2a_n - 1 – a_n -2, n ≥ 2, given a₀ = 40, a₁ = 37. Characteristic polynomial: x^2 - 2 + 1 How ...

**Discrete Math**

Oh I feel dumb. . . Ok so now a_n = C_1(1)^n + C_2(-6)^n a0 = C_1 + C_2 = 5 (1) a1 = C_1 - 6C_2 = 19 (2) So to find C1 I eliminated it by 6(1) + (2) <--is this allowed? (6C1 + 6C2) = 30 + (C1 - 6C2) = 19 ___________________ 7C1 = 49 C1 = 7 Plug this into (1) and this is ...

**Discrete Math**

Thank you so much for your help! I think I am getting the hang of it better. Can you please check: Solve the recurrence relation a_n = -5a_n - 1 + 6a_n - 2, n ≥ 2, given a₀ = 5, a₁ = 19. characteristic polynomial is x^2 + 5x - 6 it has the distinct root 2 and...

**Discrete Math**

Oops posted twice. . .Sorry

**Discrete Math**

If you don't mind can you help with this problem? Solve the recurrence relation an+1 = 7an – 10an - 1, n ≥ 2, given a₁ = 10, a₂ = 29. The characteristic polynomial is x^2 - 7 + 10 with characteristic roots 2 and 5. Once again I get confused when I ...

**Discrete Math**

Solve the recurrence relation a_n = -6a_n - 1 + 7a_n-2, n ≥ 2, given a₀ = 32, a₁ = -17. This is what I have figured out so far: polynomial: x² + 6x - 7 distinct roots: 1 and -7 I do not understand how to find C₁ and C₂. How do I complete this...

**Discrete Math**

Sorry I still don't get it. Can someone please explain?

**Discrete Math**

Solve the recurrence relation a_n = -2a_n-1 + 15a_n-2, n ≥ 2, given a₀ = 1, a₁ = -1. x² + 2x - 15, the distinct roots 3 and -5, so a_n = C₁(3^n) + C₂(-5)^n. The initial condition gives a₀ = 1 = C₁ - C₂, a₁ = -1 = 3C&#...

**Discrete Math**

REVISED QUESTION: Why use mathematical induction to prove the sum of a sequence is valid?

**Discrete Math**

Why use mathematical induction to get the sum of a sequence? Also, if there are any websites you can recommend that will be a help too. However, I need an explanation rather than examples. Thank you for any helpful replies.

**Math**

So, this is how far I got. . .I getting weird numbers. . . -3072(1 - (-1/2)⁹) ------------------- = 1 - (-1/2)

**Math**

Thank you for responding. Hmm... IDK. . .I'll have to ask if that's a typo on the other end. Hey do you mind seeing if this is correct, and helping with the second part? Consider the geometric sequence that begins -3072 and common ratio –1/2. Find the 13th and ...

**Math**

Can someone please calculate this: 48(-1/2)^6 The answer is 3/2, but I get 3/4. What am I dong wrong?

**Discrete Math**

OK thank you!

**Discrete Math**

I want to verify that this is correct: An arithmetic sequence begins, 116, 109, 102 • Determine whether -480 belongs to this sequence, if it does, what is its term number? -480 = 116 + (n - 1)(-7) n - 1 = 85.142. . . So, that means -480 does not belong to this sequence, ...

**Discrete Math**

Thank you!

**Discrete Math**

An arithmetic sequence begins, 116, 109, 102 Find the 300th term of this sequence.

**Discrete Math**

Yes, they both follow the same recursive definition. I was just trying the second part on my own to see if I understand. Sorry about the misunderstanding. . .

**Discrete Math**

f(n) is defined recursively by f(0) = 1 and for n = 0, 1, 2, . . . Find f(1), f(2), f(3)

**Discrete Math**

Oops. . .Sorry disregard previous post. . .

**Discrete Math**

OK example: f(n+1) = 3f(n) f(1) = 3 f(2) = 6 f(3) = 9 Right?

**Discrete Math**

The f(n+1) is throwing me off what does that mean?

**Discrete Math**

Ok thank for the responses, but there seems to be a contradiction between the two. Wouldn't f(1) = 1 + 2, which equals 3?

**Discrete Math**

Find f(1), f(2), and f(3) if f(n) is defined recursively by f(0) = 1 and for n = 0, 1, 2, . . . • f(n+1) = f(n) + 2 So, would it be f(n) = f(n+1) + 2? Or would I just keep it like the original and plug in 1, 2, 3. Thanks for any helpful replies.

**Discrete Math**

Here is the solution: The mistake is in applying the inductive hypothesis to look at max(x −1, y −1) . Notice that we are doing induction on n not on x or y. Even though x and y are positive integers, x −1 and y −1 need not be (one or both could be 0). ...

**Discrete Math**

Oh okay. . .I get it. . .Thank you so much for your help :)

**Discrete Math**

Thank you! So, going back to your counterexample in post 9:52: x=4, y=6, n=max(x,y)=6 Why does it =6? Sorry if this seems like a silly question. . .

**Discrete Math**

No, the question verbatim is "What is wrong with this proof?"

**Discrete Math**

Thank you for responding. Yes everything is typed correctly. I want to find what is wrong with proof.

**Discrete Math**

Theorem: For every integer n, if x and y are positive integers with max(x, y) = n, then x = y. Basic Step: Suppose that n = 1. If max(x, y) = 1 and x and y are positive integers, we have x = 1 and y = 1. Inductive Step: Let k be a positive integer. Assume that whenever max(x, ...

**Discrete Math**

Use mathematical induction to prove the truth of each of the following assertions for all n ≥1. 5^2n – 2^5n is divisible by 7 If n = 1, then 5^2(1) - 2^5(1) = -7, which is divisible by 7. For the inductive case, assume k ≥ 1, and the result is true for n = k; ...

**Discrete Math**

Any suggestions?

**Discrete Math**

Yea that's what I thought. . .Hey if you don't mind helping me further I have been working on this problem for a while and I am a bit stuck. IDK where to go from here or if I am doing it correctly: Use mathematical induction to prove the truth of each of the following ...

**Discrete Math**

Ok thank you for your helpful response! I have a couple of questions though. . . Is the 15th line suppose to be '(k+1)(k+2)/(22k+3)'? Also, the 16th line = RS, which is what exactly?

**Discrete Math**

Use mathematical induction to establish the following formula. n Σ i² / [(2i-1)(2i+1)] = n(n+1) / 2(2n+1) i=1 Thanks for any helpful replies :)

**Discrete Math**

Any suggestions?

**Discrete Math**

Thank you so much for your response! But I have completed that particular question. However, can you please help with this one? I am confused. . . Use mathematical induction to establish the following formula. n Σ i² / [(2i-1)(2i+1)] = n(n+1) / 2(2n+1) i=1 Thanks for...

**Discrete Math**

Use mathematical induction to prove the truth of each of the following assertions for all n ≥1. n³ + 5n is divisible by 6 I really do not understand this to much. This is what I have so far: n = 1, 1³ - 5(1) = 6, which is divisible by 6 Then I really don't ...

**Discrete Math**

OK you gave me a lot to think about. . .Thank you so much for your help. Until next time (which may be tomorrow). Thanks again :)