Math Problem Statement

tx'=x+2sqrt(tx)

Solution

The given differential equation is:

tx=x+2txt x' = x + 2\sqrt{tx}

Where xx' denotes the derivative of xx with respect to tt.

Let's work through solving this step by step.

Step 1: Rewrite the equation

First, divide through by tt to isolate xx' on the left-hand side:

x=xt+2txtx' = \frac{x}{t} + \frac{2\sqrt{tx}}{t}

Simplify the second term:

x=xt+2txtx' = \frac{x}{t} + \frac{2}{\sqrt{t}} \cdot \sqrt{\frac{x}{t}}

Step 2: Substitution

Let’s introduce a substitution to simplify the equation. Set v(t)=x(t)/tv(t) = \sqrt{x(t)/t}, which means:

x(t)=v(t)2tx(t) = v(t)^2 t

Now differentiate x(t)x(t) with respect to tt:

x=2v(t)v(t)t+v(t)2x' = 2v(t) v'(t) t + v(t)^2

Substitute this expression for xx' back into the original equation:

2v(t)v(t)t+v(t)2=v(t)2t+2v(t)2v(t) v'(t) t + v(t)^2 = v(t)^2 t + 2v(t)

Step 3: Simplify and solve

Now, simplify the equation:

2v(t)v(t)t=2v(t)2v(t) v'(t) t = 2v(t)

Cancel 2v(t)2v(t) from both sides (assuming v(t)0v(t) \neq 0):

v(t)t=1v'(t) t = 1

This is a separable differential equation. Solve for v(t)v(t):

v(t)=1tv'(t) = \frac{1}{t}

Integrating both sides with respect to tt:

v(t)=lnt+Cv(t) = \ln|t| + C

Step 4: Back-substitute for x(t)x(t)

Recall that v(t)=x(t)/tv(t) = \sqrt{x(t)/t}, so:

x(t)t=lnt+C\sqrt{\frac{x(t)}{t}} = \ln|t| + C

Square both sides:

x(t)t=(lnt+C)2\frac{x(t)}{t} = (\ln|t| + C)^2

Finally, multiply by tt:

x(t)=t(lnt+C)2x(t) = t (\ln|t| + C)^2

Final Solution:

The general solution to the differential equation is:

x(t)=t(lnt+C)2x(t) = t (\ln|t| + C)^2

Would you like further clarification or details on any step? Here are five related questions to explore the topic further:

  1. How do you solve separable differential equations?
  2. What other substitution techniques are commonly used in solving differential equations?
  3. How does the method of integrating factors apply to first-order linear differential equations?
  4. Can the solution to this differential equation be used for specific initial conditions?
  5. How does one handle boundary conditions in non-linear differential equations?

Tip: Substitution is a powerful method for simplifying complex differential equations—always look for opportunities to reduce terms to familiar forms.

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Math Problem Analysis

Mathematical Concepts

Differential Equations
Separable Differential Equations
Substitution Method

Formulas

x' = x/t + 2/sqrt(t) * sqrt(x/t)
v'(t) = 1/t
x(t) = t(ln|t| + C)^2

Theorems

Method of Substitution
Separation of Variables

Suitable Grade Level

University Level (Calculus II or III)