# physicsgirl

### Which of the following integrating factors makes the equation -xsinydx + (2+x)cosydy = 0 exact?

a. u = 1

b. u = x

c. u = e^x

d. u = (x+2)/e^x

1 AnswerMathematics7 years ago### The form of the solution to 2(dy/dt) + 3y = e^-t , y(0)=5 is...?

a. Ae^-1.5t + Be^-t

b. Ae^-1.5t + Bte^-t

d. Ae^1.5t + Bte^-t

Mathematics7 years ago### Which of the following apply to the equation xcos(y)y' + siny = 0?

a. linear, exact, not separable

b. linear, exact, separable

c. linear, separable, not exact

d. linear, not exact, not separable

e. nonlinear, exact, not separable

f. nonlinear, exact, separable

g. nonlinear, separable, not exact

h. nonlinear, not exact, not separable

Hint: it's definitely not d.

1 AnswerMathematics7 years ago### Which of the following apply to the equation x^2 (dy/dx) + cosx + y = 0?

a. linear, exact, not separable

b. linear, exact, separable

c. linear, separable, not exact

d. linear, not exact, not separable

e. nonlinear, exact, not separable

f. nonlinear, exact, separable

g. nonlinear, separable, not exact

h. nonlinear, not exact, not separable

1 AnswerMathematics7 years ago### Compute the inverse Laplace transform of (3s-2)/[(s+1)^2 * s]?

1 AnswerMathematics7 years ago### Compute the convolution product of -3sin(t)*cos(2t)?

1 AnswerMathematics7 years ago### Compute inverse Laplace transform of?

1. (2s+5)/s(s^2+1)

2. (2s^2+13s+5)/(s+3)(s-1)^2

1 AnswerMathematics7 years ago### Compute the laplace transform of?

1. cost(t)sin(t)

2. cos^2(t)

Hint: first use trig identities.

1 AnswerMathematics7 years ago### Can you help express the solution of the initial value problem in terms of a convolution integral?

y" + 2y' + 2y = sin(at), y(0)=0, y'(0)=0

y" + y' + (5/4)y = 1 - u_pi (t), y(0)=1, y'(0)=-1

Please show all steps!

1 AnswerMathematics7 years ago### FInd the solution of the initial value problem?

y''' - 3y'' + 2y' = t + e^t

y(0) = 1

y'(0) = -1/4

y''(0) = -3/2

Please show all steps!

1 AnswerMathematics8 years ago### Determine Y(t) of y^4 - 2y'' + y = e^t + sint if the method of undetermined coefficients is to be used?

Please show all steps.

1 AnswerMathematics8 years ago### FInd the solution of the initial value problem?

y''' - y'' + y' - y = 0

y(0) = 2

y'(0) = -1

y''(0) = -2

I'm mainly stuck on how to get the r values from the characteristic equation.

Please show all steps!

[The answer is: y = 2cos(t) - sin(t) ]

1 AnswerMathematics8 years ago### Find the general solution of the differential equations?

1) y" + y = tan(t), 0 < t < pi/2. [The answer is y= c1cos(t) + c2sin(t) - (cos(t)) ln(tan(t) + sec(t))]

2) y" - 5y' +6y = g(t), where g is an arbitrary continuous function. [The answer is y=c1e^2t + c2e^3t + integral[e^3(t-s) - e^2(t-s)]g(s)ds]

Please show all steps! Thanks in advance.

1 AnswerMathematics8 years ago### Solve the initial value problem: 9y" - 12y' + 4y = 0, y(0) = 2, y'(0) = -1?

Please show all steps.

The answer is y = 2e^(2t/3) - (7/3)te^(2t/3), but I'm having trouble getting there.

I know that r1 = 2/3 = r2, so there are repeated roots.

Then I was using y = v(t) e^(2t/3), y' = v'(t) e^(2t/3) + (2/3)v'(t)e^(2t/3)

I was having trouble finding y".

Then I would sub that back into the original equation.

Is that right? And where do I go from here?

1 AnswerMathematics8 years ago### FInd the solution of the initial value problem?

y" + 2y' + 2y = 0, y(pi/4) = 2, y(pi/4) = -2

Please show all steps.

1 AnswerMathematics8 years ago### Find the general solution of differential equation?

y" - 3y' + 2y = 2e^t

Please show all steps

2 AnswersMathematics8 years ago### How do I make Siri autocorrect certain words?

For instance, whenever I say "sail" when I'm reading a text, she types "sale". How do I get her to autocorrect "sale" to "sail"?

I already tried putting a shortcut in the keyboard shortcut settings that autocorrects "sale" to "sail" when I am typing out a text. However when I'm using Siri to type m texts for me, she doesn't autocorrect the word..HELP!

1 AnswerMedia & Journalism8 years ago### Find the general solution of the following differential equations:?

1. y" + y = tant, 0<t<pi/2

2. y" - 5y' + 6y = g(t)

Please show all steps!

1 AnswerMathematics8 years ago### FInd the solution of the initial value problem?

y" + 2y' + 5y = (4e^-t)(cos2t), y(0)=1, y'(0)=0

Please show all steps!

1 AnswerMathematics8 years ago