Answered

. Solve the following initial value problem: (t2−20t+51)dydt=y (t2−20t+51)dydt=y with y(10)=1y(10)=1. (Find yy as a function of tt.)

Answer :

lublana

Answer:

[tex]y=(\frac{t-17}{t-3})^{\frac{1}{14}}[/tex]

Step-by-step explanation:

We are given that initial value problem

[tex]t^2-20t+51)\frac{dy}{dt}=y[/tex]

[tex]\frac{dy}{y}=\frac{dt}{t^2-20t+51}[/tex]

[tex]\frac{dy}{y}=\frac{dt}{t^2-3t-17t+51}[/tex]

[tex]\frac{dy}{y}=\frac{dt}{(t(t-3)-17(t-3)}[/tex]

[tex]\frac{dy}{y}=\frac{dt}{(t-3)(t-17)}[/tex]

[tex]\frac{1}{(t-3)(t-17)}=\frac{A}{t-3}+\frac{B}{t-17}[/tex]

[tex]\frac{1}{(t-3)(t-17)}=\frac{A(t-17)+B(t-3)}{(t-3)(t-17)}[/tex]

[tex]1=A(t-17)+B(t-3)[/tex]...(1)

Substitute t-3=0

t=3

t-17=0

t=17

Substitute t=3 in equation (1)

[tex]1=A(3-17)+0[/tex]

[tex]1=-14A[/tex]

[tex]A=-\frac{1}{14}[/tex]

Substitute t=17

[tex]1=B(17-3)[/tex]

[tex]1=14B[/tex]

[tex]B=\frac{1}{14}[/tex]

Substitute the values of A and B

[tex]\frac{1}{(t-3)(t-17)}=-\frac{1}{14}(\frac{1}{t-3})+\frac{1}{14}(\frac{1}{t-17})[/tex]

[tex]\int\frac{dy}{y}=-\frac{1}{14}\int\frac{dt}{t-3}+\frac{1}{14}\int\frac{dt}{t-17}[/tex]

[tex]ln y=-\frac{1}{14}ln\mid{t-3}\mid+\frac{1}{14}\mid{t-17}\mid+ln C[/tex]

By using formula:[tex]\frac{dx}{x}=ln x+C[/tex]

[tex]ln y=\frac{1}{14}(-ln\mid{t-3}\mid+ln\mid{t-17}\mid)+ln C[/tex]

Using formula:[tex]ln x-ln y=ln \frac{x}{y}[/tex]

[tex]ln y=\frac{1}{14}(ln\mid{\frac{t-17}{t-3}}\mid)+ln C[/tex]

[tex]ln y=\frac{1}{14}ln\mid{\frac{t-17}{t-3}}\mid+ ln C[/tex]

Substitute y(10)=1

[tex]ln 1=\frac{1}{14}ln\mid\frac{10-17}{10-3}\mid+ln C[/tex]

[tex]0=0+ln C[/tex]

Because ln 1=0

[tex]lnC=0[/tex]

[tex]C=e^0=1[/tex]

Because [tex]ln x=y\implies x=e^y[/tex]

Substitute the value of C

[tex]ln y=\frac{1}{14}ln\mid\frac{t-17}{t-3}\mid+ln1[/tex]

[tex]ln y=\frac{1}{14}ln\mid\frac{t-17}{t-3}\mid+0[/tex]

[tex]ln y=\frac{1}{14}ln\mid\frac{t-17}{t-3}\mid[/tex]

[tex]14ln y=ln\mid\frac{t-17}{t-3}\mid[/tex]

[tex]lny^{14}=ln\mid\frac{t-17}{t-3}\mid[/tex]

By using identity [tex]blog a= loga^b[/tex]

[tex]y^{14}=\frac{t-17}{t-3}[/tex]

[tex]y=(\frac{t-17}{t-3})^{\frac{1}{14}}[/tex]

The function y as a function of t is [tex]\rm y=(\dfrac{t-17}{t-3})^{\frac{1}{14}}[/tex]

Given that

The differential equation is;

[tex]\rm (t^2-20t+51)\dfrac{dy}{dt}=y[/tex]

With y(10)= 1 y(10) =1.

We have to find

The function y is a function of t.

According to the question

The differential equation is;

[tex]\rm (t^2-20t+51)\dfrac{dy}{dt}=y[/tex]

Solving the given differential equation

[tex]\rm (t^2-20t+51)\dfrac{dy}{dt}=y\\ \\ \dfrac{dy}{y} =\dfrac{dt}{ (t^2-20t+51)}\\ \\ \dfrac{dy}{y} =\dfrac{dt}{ (t^2-3t-17t+51)}\\\\ \dfrac{dy}{y} =\dfrac{dt}{ t(t-3)-17(t-3)}\\\\ \dfrac{dy}{y} =\dfrac{dt}{ (t-3)(t-17)}\\\\ \dfrac{1}{ (t-3)(t-17)} = \dfrac{A}{t-3} + \dfrac{B}{t-17}\\ \\ \dfrac{1}{ (t-3)(t-17)} = \dfrac{A(t-17)+B(t-3)}{ (t-3)(t-17)}\\ \\ 1 = A(t-17)+B(t-3) \\ [/tex]

Here, t-3 = 0, t =3

And t-17=0, t = 17

Substitute t =3 in the equation;

[tex]\rm 1 = A(t-17)+B(t-3)\\\\ 1 = A(3-17)+B(3-3)\\ \\ 1 = -14A+0\\ \\ A = \dfrac{-1}{14}[/tex]

Substitute t =17 in the equation;

[tex]\rm 1 = A(t-17)+B(t-3)\\\\ 1 = A(17-17)+B(17-3)\\\\1 = 0+14B\\\\B= \dfrac{1}{14}[/tex]

Substitute the values of A and B in the equation;

[tex]\rm \dfrac{1}{ (t-3)(t-17)} = \dfrac{A}{t-3} + \dfrac{B}{t-17}\\\\ \\ \dfrac{1}{ (t-3)(t-17)} ={\dfrac{-1}{14}} \left(\dfrac{1}{t-3} \right) + \dfrac{1}{14} \left (\dfrac{B}{t-17} \right )\\\\\\ \dfrac{dy}{y} ={\dfrac{-1}{14}} \left(\dfrac{1}{t-3} \right) + \dfrac{1}{14} \left (\dfrac{1}{t-17} \right )[/tex]

Integrating the equation both the sides;

[tex]\rm \int\dfrac{dy}{y} ={\dfrac{-1}{14}} \int \left(\dfrac{dt}{t-3} \right) + \dfrac{1}{14} \int \left (\dfrac{dt}{t-17} \right )\\\\ lny = \dfrac{-1}{14} }ln\mid{t-3}\mid+\frac{1}{14}\mid{t-17}\mid+ln C[/tex]

By using the formula;

[tex]\rm ln x-ln y=ln \frac{x}{y}\\\\ \rm ln y=\dfrac{1}{14}(ln\mid{\frac{t-17}{t-3}}\mid)+ln C\\\\ ln y=\dfrac{1}{14}ln\mid{\frac{t-17}{t-3}}\mid+ ln C\\\\ \rm Substitute \ y(10)=1\\\\ ln 1=\dfrac{1}{14}ln\mid\frac{10-17}{10-3}\mid+ln C\\\\ 0=0+ln C\\\\Because\ ln 1=0\\\\lnC=0\\\\ C=e^0=1[/tex]

Now substitute the value of c in the equation;

[tex]\rm ln y=\frac{1}{14}ln\mid\frac{t-17}{t-3}\mid+ln1 ln y=\frac{1}{14}ln\mid\frac{t-17}{t-3}\mid+0\\\\ ln y=\frac{1}{14}ln\mid\frac{t-17}{t-3}\mid\\\\ 14ln y=ln\mid\frac{t-17}{t-3}\mid\\\\ lny^{14}=ln\mid\frac{t-17}{t-3}\mid\\\\[/tex]

By using log identity y as a function of t is;

[tex]\rm blog a= loga^b\\\\\ y^{14}=\dfrac{t-17}{t-3}\\\\ y=(\dfrac{t-17}{t-3})^{\frac{1}{14}}[/tex]

Hence, the function y as a function of t is [tex]\rm y=(\dfrac{t-17}{t-3})^{\frac{1}{14}}[/tex]

To know more about Differential Equation click the link given below.

https://brainly.com/question/14802306

Other Questions