Find the function F that satisfies the following differential equations

abreviatsjw

abreviatsjw

Answered question

2021-12-31

Find the function F that satisfies the following differential equations and initial conditions.
F(x)=cosx,F(0)=3,F(π)=5

Answer & Explanation

Cassandra Ramirez

Cassandra Ramirez

Beginner2022-01-01Added 30 answers

Step 1
Given that,
(1) f(x)=cosx
(2) f(0)=3
(3) f(π)=5
Integrate equation 1;
fx)dx=cos(x)dx
f(x)=sin(x)=sin(x)+c (4)
Using criteria (2);
f(0)=sin(0)+c
3=0+c
c=3
Equation (4) is are written as,
f(x)=sin(x)+3 ..(5)
Step 2
Integrate equation 5;
f(x)dx=[sin(x)+3]dx
f(x)=cos(x)+3x+c (5)
Using criteria (3),
f(π)=cos(π)+3π+c
5=1+3π+c
c=43π
Equation (5) is are written as,
f(x)=cos(x)+3x+43π

Nadine Salcido

Nadine Salcido

Beginner2022-01-02Added 34 answers

As we know Fx)=ddxF(x). Therefore, F'(x) is an antiderivative of F"(x).
F(x)=Fx)dx=cosxdx=sinx+C1 (2)
Taking into account that F(0)=3 we have:
F(0)=3sin(0)+C1=3C1=3 (3)
Then F(x)=sinx+3
Since F(x)=ddxF(x) we have that:
F(x)=F(x)dx=(sinx+3)dx
=sinxdx+3dx (4)
=cosx+3x+C2
Since F(π)=4 we have that
F(π)=4cos(π)+3(π)+C2=4
1+3π+C2=4 (5)
C2=3(1π)
Finally, we have found that
F(x)=cosx+3x+3(1π) (6)
karton

karton

Expert2022-01-10Added 613 answers

From the given conditions we have
F(x)=cosxdx=sinx+C
Now if we include that F(0)=3, we have
3=F(0)=C
that is, C=3, which means that F(x)=sinx+3
Now we have that
F(x)=(sinx+3)dx=sinxdx+3dx=cosx+3x+D
From the given condition we get
4=F(π)=1+3π+D
that is, D=33π, so F(x)=cosx+3x+33π

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