Consider the first order separable equation y′=20x^4y(1+3x^5)^1/3. An explicit general solution can be written in the form y=Cf(x) for some function f(x) with C an arbitrary constant. Here f(x)=_______

Next find the explicit solution of the initial value problem y(0)=3
y=_________ .

Respuesta :

Answer:

[tex]f(x)=Ce^{(1+3x^5)^{\frac{4}{3}}}[/tex]

The explicit solution of the initial value problem=y=[tex]1.1e^{(1+3x^5)^{\frac{4}{3}}}[/tex]

Step-by-step explanation:

We are given that first order separable equation

[tex]\frac{dy}{dx}=20x^4y(1+3x^5)^{\frac{1}{3}}[/tex]

[tex]\int \frac{dy}{y}=20\int x^4(1+3x^5)^{\frac{1}{3}}dx[/tex]

Suppose [tex]1+3x^5=t[/tex]

Differentiate w.r.t x

[tex]15x^4dx=dt[/tex]

[tex]x^4dx=\frac{1}{15}dt[/tex]

Substitute the values

[tex]ln y=\frac{20}{15}\int t^{\frac{1}{3}}dt[/tex]

[tex]ln y=\frac{4}{3}\times \frac{3}{4} t^{\frac{4}{3}}[/tex]+C

By using the formula [tex]\int x^n dx=\frac{x^{n+1}}{n+1}[/tex]+C

[tex]\int \frac{dx}{x}=ln x+C[/tex]

[tex]ln y=(1+3x^5)^{\frac{4}{3}}[/tex]+C

[tex]y=e^{(1+3x^5)^{\frac{4}{3}}+C}[/tex]

By using identity :[tex]ln x=y\implies x=e^y[/tex]

[tex]y=e^{(1+3x^5)^{\frac{4}{3}}}\cdot e^C=Ce^{(1+3x^5)^{\frac{4}{3}}}[/tex]

By using identity :[tex]x^a\cdot x^y=x^{a+y}[/tex]

Where [tex]e^C=C[/tex]

[tex]y=Ce^{(1+3x^5)^{\frac{4}{3}}}[/tex]

By compare with y=Cf(x)

We get [tex]f(x)=Ce^{(1+3x^5)^{\frac{4}{3}}}[/tex]

We are given that y(0)=3

Substitute the value

[tex]3=Ce[/tex]

[tex]C=\frac{3}{e}=1.1[/tex]

Substitute the value

[tex]y=1.1e^{(1+3x^5)^{\frac{4}{3}}}[/tex]

The explicit solution of the initial value problem=y=[tex]1.1e^{(1+3x^5)^{\frac{4}{3}}}[/tex]