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Differential Equations/Questions
| Subject | Date Asked | Expert |
| A problem | 1/31/2012 | Scott A Wilson |
| Q: Hey, I'm having really hard time with this question. Please help. Find an ODE of the form dy dx = ... A: Let the function be 3 - 5^(-x). Let infinity be oo. If we look at the lim(x->oo), the power of 5 ... | ||
| The existence of a solution of 1st order ODE's | 1/21/2012 | Scott A Wilson |
| Q: Wilson, In the case of a first order ODE of the form y'=f(x,y), is the continuity of f SUFFICIENT to ... A: Yes, it has been shown that a solution exists. Look at ... | ||
| Solving polynomial simultaneous equations using matrices | 1/6/2012 | Abe Mantell |
| Q: I have a project in which i need to model a population-time curve. I have chosen quadratic equations ... A: The three data points you have slected give the three linear equations for a,b, and c. For the RREF ... | ||
| Differentials | 12/21/2011 | Scott A Wilson |
| Q: Sir, dy/dx means rate of change of y wrt x. So dy or dx cannot be taken independently. But in ... A: I believe that last sentence is true. If we have a function, f(x), if there is a df on one side of ... | ||
| Elasticity | 12/14/2011 | Scott A Wilson |
| Q: my question is regarding solving price elasticity of supply for a quadratic equation, for example Q ... A: Elasticity has to do with the derivative at a point. If the equation for quantity is Q = 7 + P + ... | ||
| differential equation | 11/4/2011 | Scott A Wilson |
| Q: Is the answer provided correct ?? Thanks A: I did (1) and (3), since (2) seemed like I needed to think about it for awhile, and then I saw that ... | ||
| Limits tending to infinity | 10/11/2011 | Scott A Wilson |
| Q: lim x->0(x/x)=1. What will happen when I do like this...lim x->0(x)lim x->0(1/x)=?( Is the answer 1 ... A: The lim x->0 of x is 0. The lim x->0 of 1/x is infinity. When multiplied together, we get ... | ||
| systems of diffrantial equations | 10/7/2011 | Dr Paul Safier |
| Q: I have a set of partial equations that I need to solve in order to fit with my experimental data. ... A: Sajjad, OK, thanks. So this is a system of two ordinary (not partial) differential equations for ... | ||
| systems of diffrantial equations | 10/7/2011 | Dr Paul Safier |
| Q: I have a set of partial equations that I need to solve in order to fit with my experimental data. ... A: I'm not seeing that this is a partial differential equation. Can you clarify what you mean by the ... | ||
| differential equations | 9/23/2011 | Dr Paul Safier |
| Q: question is in the image A: J, Your equation is close to being exact, but not quite. To make it exact, you multiply each term ... | ||
| decay and growth rate | 9/13/2011 | Dr Paul Safier |
| Q: A public awareness and education campaign causes the contagiousness of a disease to decrease ... A: J, The differential equation is separable, so move the term with P over to the left and integrate ... | ||
| Particular Solution of the ODE | 8/14/2011 | Dr Paul Safier |
| Q: Im working on the particular solution for this equation: y'' +4y =16cos(2x). I tried the y =acos2x + ... A: Jay, The way I chose to handle that integral was to rewrite the cos^2(2x) term using the ... | ||
| Particular Solution of the ODE | 8/10/2011 | Dr Paul Safier |
| Q: Im working on the particular solution for this equation: y'' +4y =16cos(2x). I tried the y =acos2x + ... A: Jay, Sorry for the late response. The solution to the differential equation is: y = c1 sin(2x) + ... | ||
| what substitution should i make? | 8/5/2011 | Abe Mantell |
| Q: My equation that im dealing with is: yy' =(x-1)e^-y^2. The aim is to find the particular solution ... A: For the DE: yy' =(x-1)e^(-y^2), it is separable! ==> y dy/dx = (x-1) e^(-y^2), multiply by e^(y^2) ... | ||
| rational expressions | 8/3/2011 | Abe Mantell |
| Q: i am studying for a compass exam and have gotten stuck with rational expressions! The original ... A: Factor! r^2-5r+6 = (r-3)(r-2) r^2-4 = (r+2)(r-2) So, the ratio is: (r-3)(r-2) ----------, which ... | ||
| PBL maths project | 7/29/2011 | Dr Paul Safier |
| Q: A certain radioactive material is known to decay at a rate proportional to the amount present. A ... A: Chung, From (a), (b) and (c), we get that m(t=80)=64g. The equation in (d) should be dm/dt = ... | ||
| Power series solution for differential equation | 7/29/2011 | Dr. Nyayapati Swami |
| Q: The problem: Solve the fluxional equation (y with a dot on top)/(x with a dot on top) = 2/x + 3 - ... A: Replacing x by x+1 changes to eqn to dy/dx = 2/(x+1) + 3 - (x + 1)^2 [note dy/d(x+1) = dy/dx) ... | ||
| Power series solution for differential equation | 7/29/2011 | Scott A Wilson |
| Q: The problem: Solve the fluxional equation (y with a dot on top)/(x with a dot on top) = 2/x + 3 - ... A: If (y dot)/(x dot) is dy/dx, then we have dy/dx = 2/x + 3 - x^2. What is the reason for putting in ... | ||
| power series solutions of ODE's and the convergence problem | 7/24/2011 | Scott A Wilson |
| Q: I would like an explaination of the following: let the IVP y'+p(x)y=0 , y(x0)=y0 where P(x) is ... A: A power series and a function are the same. There is a power series for e^x, and that is e^x = ... | ||
| power series solutions of ODE's and the convergence problem | 7/23/2011 | Scott A Wilson |
| Q: I would like an explaination of the following: let the IVP y'+p(x)y=0 , y(x0)=y0 where P(x) is ... A: For the solution to y' + p(x)y = 0, this can be rewritten as y' = -p(x)y. Dividing both sides by y ... | ||
| Ordinary differential equaitons | 7/21/2011 | Abe Mantell |
| Q: I was hoping you could help me with this differential equation. My equation is dy/dx = y/x + 2*x^3/y ... A: Yes, I see what you mean. Instead, try the following... Notice we can rewrite the DE as: dy/dx = ... | ||
| Power Series Differential Equation Problem | 7/13/2011 | Dr Paul Safier |
| Q: Dr. Safier, Me and my study group were given a differential equation to solve using the method of ... A: Andrew, So, I approximated e^x as (1+x), then multiplied that by the series for y'. y' = ... | ||
| Power Series Differential Equation Problem | 6/26/2011 | Dr Paul Safier |
| Q: Dr. Safier, Me and my study group were given a differential equation to solve using the method of ... A: Andrew, Sorry for the late reply on this; I missed the notification from the website. This is a ... | ||
| Please Help Solve! | 6/26/2011 | Abe Mantell |
| Q: Dr. Mantell, We were trying to solve this differential equation in class last week and me and my ... A: Start by letting y(x)=SIGMA(a_n x^n, n=0 to infinity), as usual, then use the power series for e^x, ... | ||
| algebra | 6/25/2011 | Dr Paul Safier |
| Q: I can't figure this out, I understood that x=1 but I'm new at this can you help step by step x: ... A: Carolina, Start with 5x-(2-9x) = 14x+2(x-10) Simplify each side to get: 5x - 2 + 9x = 14x + 2x - ... | ||
| quasi linear equations | 6/17/2011 | Dr Paul Safier |
| Q: how quasi linear equations are different from heat equations, wave equations and Laplace ... A: Nabila, Quasilinear equations (as opposed to linear or nonlinear) don't have the nonlinear term ... | ||
| small doubt | 6/11/2011 | Abe Mantell |
| Q: Whether Domain of a logarthmicfunction is the range of a exponentialfunction?if so can we treat ... A: The domain of f(x)=ln(x) is x>0...the range of f(x)=e^x is y>0...so yes, the domain of ln(x) and the ... | ||
| linear functions | 5/27/2011 | Scott A Wilson |
| Q: i have another question. I came across this one problem, and i am not sure what to do. I tried it by ... A: Since the two equations are 2.3 + 0.4t and 1.2 + 0.6t, where t is the years from now, find where ... | ||
| Differential equation | 5/18/2011 | Dr Paul Safier |
| Q: Solve:- x^2 d2y/dx2 x dy/dx - y = x^3 ANSWER: Manav, I didn't hear back from you on the missing ... A: Manav, Your equation is of the Euler Cauchy type. It's non-homogeneous. The solution technique is ... | ||
| Differential equation | 5/15/2011 | Dr Paul Safier |
| Q: Solve:- x^2 d2y/dx2 x dy/dx - y = x^3 A: Manav, I didn't hear back from you on the missing sign in your equation. I went ahead and assumed ... | ||
| Differential equation | 5/15/2011 | Scott A Wilson |
| Q: If D denotes d/dx, solve the following differential equation:- (D^3 + 2D^2 + D)y = e^2x + x^2 + ... A: For a solution, I get the following with constants [C1], [C2], [C3], and [C4]: y = [C1] + [C2]e^-x ... | ||
| word problem | 4/1/2011 | Dr Paul Safier |
| Q: I have a rather easy ODE problem, but I'm not understanding the answer my book gives. The problem ... A: Sam, The answer in the book is correct. The difference is in the integration of the term 1/(v-49). ... | ||
| Differential Equation Help | 3/23/2011 | Scott A Wilson |
| Q: Knowing that all members of the family y = (6)^1/2 * (c - x^2)^-1/2 are solutions of the ... A: Note that 1/2 is the same as 0.5 and a negative exponet becomes positive when moved to the ... | ||
| math | 3/23/2011 | Scott A Wilson |
| Q: Solve the differential equation ydy/dx = xe^-y for which y=0 when x =2 Thanks A: Remake the problem x dx = y e^y dy, the integrate. The left side integrates to x^2 + C. On the ... | ||
| Differential equation of s*e^(-Ls) | 3/22/2011 | Dr Paul Safier |
| Q: I am writing the code for the least square algorithm wherin I have a transfer function whose ... A: Winnie, I'm not entirely clear on what you're trying to do. Do you want to invert the function ... | ||
| Cost and revenue function | 3/12/2011 | Scott A Wilson |
| Q: A coffee powder provider works out the vairable cost of each kg is $2.50 with fixed cost of $30. He ... A: It would seem that C(x) = 30 + 2.5x and that the profit P(x) = 3x. This means to break even, we ... | ||
| Autonomous Nonlinear System of ODE | 3/4/2011 | Dr. Nyayapati Swami |
| Q: The last question in a set of homework has me stumped: Discover what you can about the system of ... A: x^3=2y^3=2(2x^3)=4x^3 x^3 - 4x^3 = 0 -3x^3=0 x=0 So x=0, y=0 is the only critical point of the ... | ||
| concave function | 2/28/2011 | Scott A Wilson |
| Q: how i can prove mathematically that the derivative of this function y=ax^b where (b<1) will give a ... A: Not exactly. If you want to say that the function f(x) [and not f'(x)] is concave up, then what is ... | ||
| concave functions | 2/28/2011 | Dr. Nyayapati Swami |
| Q: how i can prove mathematically that the derivative of this function y=ax^b where (b<1) will give a ... A: A function f(x) is concave if its second-order derivative f''(x) is negative. In your example, y = a ... | ||
| concave function | 2/27/2011 | Scott A Wilson |
| Q: how i can prove mathematically that the derivative of this function y=ax^b where (b<1) will give a ... A: Note the function is concave up when the 2nd derivative is positive and concave down when the 2nd ... | ||
Differential Equations
Answers by Expert:
Scott A Wilson
Top Expert on this page
Expertise
Most ordinary differential equations.
Experience
I have taken Differential Equations at OSU.
Occasionally I have assisted people with questions on the subject.
Publications
In the paper where MS students publish a thesis on shock waves and rarefaction fans.
Education/Credentials
MS at OSU in Mathemematics.
MS at OSU in Mathematical Science.
Awards and Honors
Graduation with honors for my BS and MS.
Past/Present Clients
I answered many questions at OSU, down in south seattle at a college, at a church in Corvallis, OR,
as Safeway in Washington, and many other areas. I have answered over 7,500 right here, but only a little over 150 of them have been in differential equations.
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