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The solution to the differential equation f’’(x)+4f’(x)+4f(x)=0 is      
  • a)
    f1(x) =  e-2x
  • b)
    f1(x) =  e2x, f2(x) = e-2x
  • c)
    f1(x) =  e-2x, f2(x) = xe-2x
  • d)
    f1(x) = e-2x, f2(x) = e-x
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
The solution to the differential equation f’’(x)+4f’...
Let y(x) = emx (m ≠ 0)be the trial soln .Auxiliary equation. m2 + 4m+ 4 = 0 ⇒(m+ 2)2 = 0
In particular, when A =1,B =1,then f(x) = (1 + x)e−2x
= e−2x + xe−2x
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The solution to the differential equation f’’(x)+4f’...
Solution to the differential equation

The given differential equation is:

f''(x) + 4f'(x) + 4f(x) = 0

This is a second-order linear homogeneous differential equation with constant coefficients.

Characteristic equation

To solve this differential equation, we first find the characteristic equation by assuming a solution of the form f(x) = e^(rx), where r is a constant.

Substituting this into the differential equation, we get:

r^2e^(rx) + 4re^(rx) + 4e^(rx) = 0

Factoring out e^(rx), we obtain:

e^(rx)(r^2 + 4r + 4) = 0

Simplifying further, we have:

(r + 2)^2 = 0

Therefore, the characteristic equation is:

r + 2 = 0

Solving for r, we find:

r = -2

Repeated root

Since we have a repeated root, the general solution to the differential equation is given by:

f(x) = (C1 + C2x)e^(-2x)

where C1 and C2 are constants.

Final answer

Given options:

a) f1(x) = e^(-2x)
b) f1(x) = e^(2x), f2(x) = e^(-2x)
c) f1(x) = e^(-2x), f2(x) = xe^(-2x)
d) f1(x) = e^(-2x), f2(x) = e^(-x)

Comparing the general solution to the given options, we can see that option 'C' matches the form:

f1(x) = e^(-2x), f2(x) = xe^(-2x)

Therefore, the correct answer is option 'C'.
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The solution to the differential equation f’’(x)+4f’(x)+4f(x)=0 is a)f1(x) = e-2xb)f1(x) = e2x, f2(x) = e-2xc)f1(x) = e-2x, f2(x) = xe-2xd)f1(x) = e-2x, f2(x) = e-xCorrect answer is option 'C'. Can you explain this answer?
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