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Which of the following is a solution to the differential equation dx(t)/dt + 3x(t) = 0?
  • a)
    x (t) = 3e-t
  • b)
    up>(b) x (t) = 2e-3t
  • c)
    x (t) = -3/2t2
  • d)
    x (t) = 3t2
Correct answer is option 'B'. Can you explain this answer?
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Which of the following is a solution to the differential equation dx(...
Solution:

Given differential equation: dx(t)/dt + 3x(t) = 0

This is a first-order linear homogeneous differential equation, where the coefficient of x(t) is a constant (3).

To solve this equation, we can use the method of separation of variables.

Separating the variables:
dx(t)/x(t) = -3dt

Now, we integrate both sides:

∫(1/x(t)) dx(t) = ∫(-3) dt

Integrating the left side gives us the natural logarithm of the absolute value of x(t):

ln|x(t)| = -3t + C1

Where C1 is the constant of integration.

Taking the exponential of both sides to eliminate the logarithm:

e^(ln|x(t)|) = e^(-3t + C1)

|x(t)| = e^(-3t) * e^(C1)

Note that e^(C1) is just a constant, so we can rewrite it as |x(t)| = Ce^(-3t), where C is a non-zero constant.

Now, we consider two cases for the constant C:

1. If C = 0, then |x(t)| = 0, which implies that x(t) = 0. However, this is not a valid solution since the initial equation would become undefined (division by zero).

2. If C ≠ 0, then |x(t)| = Ce^(-3t), and we can remove the absolute value by considering both positive and negative values of C:

x(t) = ±Ce^(-3t)

Therefore, the general solution to the given differential equation is x(t) = Ce^(-3t), where C is a non-zero constant.

Out of the given options, option B is x(t) = 2e^(-3t), which matches our general solution.

Hence, option B is the correct solution to the differential equation dx(t)/dt + 3x(t) = 0.
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Which of the following is a solution to the differential equation dx(...
We have dx(t)/dt + 3x(t) = 0
Or (D + 3)x(t) = 0
Since m = -3, x(t) = Ce-3t
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Which of the following is a solution to the differential equation dx(t)/dt + 3x(t) = 0?a)x (t) = 3e-tb)up>(b) x (t) = 2e-3tc)x (t) = -3/2t2d)x (t) = 3t2Correct answer is option 'B'. Can you explain this answer?
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