Let y=y(x)y = y(x) be the solution curve of the differential equation x(x2+ex)dy+(ex(x−2)y−x3)dx=0, x>0x(x^2 + e^x)dy + (e^x(x - 2)y - x^3)dx = 0,\ x > 0, passing through the point (1,0)(1, 0). Then y(2)y(2) is equal to:

Answer: 44+e2\frac{4}{4 + e^2}

Step-by-step solution

Step 1: Rearrange the differential equation into standard form

First, we rearrange the given differential equation to isolate the derivative term and group terms involving yy. This helps us identify if it's a linear differential equation, which can be solved using an integrating factor.

Step 2: Convert to linear first-order form

Divide the entire equation by x(x2+ex)x(x^2 + e^x) to bring it into the standard form of a linear first-order differential equation: dydx+P(x)y=Q(x)\frac{dy}{dx} + P(x)y = Q(x). Here, P(x)=ex(x−2)x(x2+ex)P(x) = \frac{e^x(x - 2)}{x(x^2 + e^x)} and Q(x)=x2x2+exQ(x) = \frac{x^2}{x^2 + e^x}.

Step 3: Calculate the integrating factor

The integrating factor (I.F.) is e∫P(x)dxe^{\int P(x)dx}. We need to evaluate the integral of P(x)P(x). Notice that the numerator ex(x−2)=xex−2exe^x(x-2) = xe^x - 2e^x is the derivative of xex−2exxe^x - 2e^x. The denominator is x(x2+ex)=x3+xexx(x^2+e^x) = x^3 + xe^x. This integral is tricky, but we can observe that the derivative of the denominator x3+xexx^3 + xe^x is 3x2+ex+xex3x^2 + e^x + xe^x. This doesn't directly simplify. Let's re-examine the numerator. The derivative of x2+exx^2 + e^x is 2x+ex2x + e^x. This also doesn't directly simplify. Let's try a different approach for the integral. Consider the derivative of ln⁡(x2+ex)\ln(x^2 + e^x). It is 2x+exx2+ex\frac{2x + e^x}{x^2 + e^x}. This is not matching. Let's try to rewrite P(x)P(x) as ex(x−2)x(x2+ex)=xex−2exx3+xex\frac{e^x(x-2)}{x(x^2+e^x)} = \frac{xe^x - 2e^x}{x^3 + xe^x}. This integral is not straightforward. Let's recheck the problem statement for any simplification. The given differential equation is x(x2+ex)dy+(ex(x−2)y−x3)dx=0x(x^2 + e^x)dy + (e^x(x - 2)y - x^3)dx = 0. This can be written as x(x2+ex)dy=−(ex(x−2)y−x3)dxx(x^2 + e^x)dy = -(e^x(x - 2)y - x^3)dx. So, dydx=x3−ex(x−2)yx(x2+ex)\frac{dy}{dx} = \frac{x^3 - e^x(x - 2)y}{x(x^2 + e^x)}. This is dydx+ex(x−2)x(x2+ex)y=x2x2+ex\frac{dy}{dx} + \frac{e^x(x - 2)}{x(x^2 + e^x)}y = \frac{x^2}{x^2 + e^x}. Let's re-evaluate the integral of P(x)P(x). We can rewrite P(x)P(x) as ex(x−2)x(x2+ex)=xex−2exx3+xex\frac{e^x(x-2)}{x(x^2+e^x)} = \frac{xe^x - 2e^x}{x^3 + xe^x}. This is not easily integrable. Let's try to rewrite the original equation in a different form. Let's try to rewrite the original equation as x(x2+ex)dy+(xex−2ex)ydx=x3dxx(x^2 + e^x)dy + (xe^x - 2e^x)y dx = x^3 dx. Divide by x2+exx^2 + e^x: xdy+xex−2exx2+exydx=x3x2+exdxx dy + \frac{xe^x - 2e^x}{x^2 + e^x} y dx = \frac{x^3}{x^2 + e^x} dx. This is not a standard form. Let's go back to the linear form: dydx+ex(x−2)x(x2+ex)y=x2x2+ex\frac{dy}{dx} + \frac{e^x(x - 2)}{x(x^2 + e^x)}y = \frac{x^2}{x^2 + e^x}. The integrating factor is e∫ex(x−2)x(x2+ex)dxe^{\int \frac{e^x(x - 2)}{x(x^2 + e^x)}dx}. Let's try to simplify the integrand: ex(x−2)x(x2+ex)=xex−2exx3+xex\frac{e^x(x - 2)}{x(x^2 + e^x)} = \frac{xe^x - 2e^x}{x^3 + xe^x}. Consider the derivative of ln⁡(x2+ex)\ln(x^2 + e^x). It is 2x+exx2+ex\frac{2x + e^x}{x^2 + e^x}. Consider the derivative of ln⁡(x)\ln(x). It is 1x\frac{1}{x}. Let's try to manipulate the integrand: ex(x−2)x(x2+ex)=ex(x2+ex)−ex(x2+2)x(x2+ex)\frac{e^x(x-2)}{x(x^2+e^x)} = \frac{e^x(x^2+e^x) - e^x(x^2+2)}{x(x^2+e^x)}. This is not working. Let's try to rewrite the original equation as x(x2+ex)dy+(xex−2ex)ydx=x3dxx(x^2 + e^x)dy + (xe^x - 2e^x)y dx = x^3 dx. This is x(x2+ex)dy+(xex−2ex)ydx=x3dxx(x^2 + e^x)dy + (xe^x - 2e^x)y dx = x^3 dx. Divide by x2x^2: (x+exx)dy+(exx−2exx2)ydx=xdx(x + \frac{e^x}{x})dy + (\frac{e^x}{x} - \frac{2e^x}{x^2})y dx = x dx. This is not a linear form. Let's re-examine the original equation: x(x2+ex)dy+(ex(x−2)y−x3)dx=0x(x^2 + e^x)dy + (e^x(x - 2)y - x^3)dx = 0. This can be written as x(x2+ex)dy+ex(x−2)ydx=x3dxx(x^2 + e^x)dy + e^x(x - 2)y dx = x^3 dx. Divide by x2x^2: (x+exx)dy+(exx−2exx2)ydx=xdx(x + \frac{e^x}{x})dy + (\frac{e^x}{x} - \frac{2e^x}{x^2})y dx = x dx. This is not a linear form. Let's try to rewrite the equation as Mdx+Ndy=0M dx + N dy = 0. M=ex(x−2)y−x3M = e^x(x - 2)y - x^3 and N=x(x2+ex)N = x(x^2 + e^x). ∂M∂y=ex(x−2)\frac{\partial M}{\partial y} = e^x(x - 2). ∂N∂x=(x2+ex)+x(2x+ex)=x2+ex+2x2+xex=3x2+ex+xex\frac{\partial N}{\partial x} = (x^2 + e^x) + x(2x + e^x) = x^2 + e^x + 2x^2 + xe^x = 3x^2 + e^x + xe^x. Since ∂M∂y≠∂N∂x\frac{\partial M}{\partial y} \neq \frac{\partial N}{\partial x}, the equation is not exact. Let's try to find an integrating factor. Consider 1N(∂M∂y−∂N∂x)=1x(x2+ex)(ex(x−2)−(3x2+ex+xex))=xex−2ex−3x2−ex−xexx(x2+ex)=−3x2−3exx(x2+ex)=−3(x2+ex)x(x2+ex)=−3x\frac{1}{N}(\frac{\partial M}{\partial y} - \frac{\partial N}{\partial x}) = \frac{1}{x(x^2 + e^x)}(e^x(x - 2) - (3x^2 + e^x + xe^x)) = \frac{xe^x - 2e^x - 3x^2 - e^x - xe^x}{x(x^2 + e^x)} = \frac{-3x^2 - 3e^x}{x(x^2 + e^x)} = \frac{-3(x^2 + e^x)}{x(x^2 + e^x)} = -\frac{3}{x}. This is a function of xx only. So, the integrating factor is e∫−3xdx=e−3ln⁡x=eln⁡x−3=x−3=1x3e^{\int -\frac{3}{x}dx} = e^{-3\ln x} = e^{\ln x^{-3}} = x^{-3} = \frac{1}{x^3}. Multiply the original equation by 1x3\frac{1}{x^3}: 1x3[x(x2+ex)dy+(ex(x−2)y−x3)dx]=0\frac{1}{x^3} [x(x^2 + e^x)dy + (e^x(x - 2)y - x^3)dx] = 0 x2+exx2dy+(ex(x−2)x3y−1)dx=0\frac{x^2 + e^x}{x^2}dy + (\frac{e^x(x - 2)}{x^3}y - 1)dx = 0 (ex(x−2)x3y−1)dx+(1+exx2)dy=0(\frac{e^x(x - 2)}{x^3}y - 1)dx + (1 + \frac{e^x}{x^2})dy = 0. Now, let M′=ex(x−2)x3y−1M' = \frac{e^x(x - 2)}{x^3}y - 1 and N′=1+exx2N' = 1 + \frac{e^x}{x^2}. ∂M′∂y=ex(x−2)x3\frac{\partial M'}{\partial y} = \frac{e^x(x - 2)}{x^3}. ∂N′∂x=x2ex−ex(2x)x4=xex−2exx3=ex(x−2)x3\frac{\partial N'}{\partial x} = \frac{x^2 e^x - e^x (2x)}{x^4} = \frac{xe^x - 2e^x}{x^3} = \frac{e^x(x - 2)}{x^3}. Since ∂M′∂y=∂N′∂x\frac{\partial M'}{\partial y} = \frac{\partial N'}{\partial x}, the equation is exact. Now we need to solve the exact differential equation. We know that there exists a function f(x,y)f(x, y) such that ∂f∂x=M′\frac{\partial f}{\partial x} = M' and ∂f∂y=N′\frac{\partial f}{\partial y} = N'. Integrate N′N' with respect to yy: f(x,y)=∫(1+exx2)dy=y+exx2y+g(x)f(x, y) = \int (1 + \frac{e^x}{x^2})dy = y + \frac{e^x}{x^2}y + g(x). Now differentiate f(x,y)f(x, y) with respect to xx and equate it to M′M': ∂f∂x=x2ex−ex(2x)x4y+g′(x)=xex−2exx3y+g′(x)\frac{\partial f}{\partial x} = \frac{x^2 e^x - e^x (2x)}{x^4}y + g'(x) = \frac{xe^x - 2e^x}{x^3}y + g'(x). We have M′=ex(x−2)x3y−1M' = \frac{e^x(x - 2)}{x^3}y - 1. So, ex(x−2)x3y+g′(x)=ex(x−2)x3y−1\frac{e^x(x - 2)}{x^3}y + g'(x) = \frac{e^x(x - 2)}{x^3}y - 1. This implies g′(x)=−1g'(x) = -1. Integrating g′(x)g'(x) with respect to xx: g(x)=∫−1dx=−x+C1g(x) = \int -1 dx = -x + C_1. So, the solution is y+exx2y−x=Cy + \frac{e^x}{x^2}y - x = C. y(1+exx2)=x+Cy(1 + \frac{e^x}{x^2}) = x + C. y(x2+exx2)=x+Cy(\frac{x^2 + e^x}{x^2}) = x + C. y=x2(x+C)x2+exy = \frac{x^2(x + C)}{x^2 + e^x}.

Step 4: Apply the initial condition

The solution curve passes through the point (1,0)(1, 0). Substitute x=1x = 1 and y=0y = 0 into the general solution to find the value of the constant CC.

Step 5: Write the particular solution

Substitute the value of C=−1C = -1 back into the general solution to obtain the particular solution for the given initial condition.

Step 6: Calculate y(2)

Finally, substitute x=2x = 2 into the particular solution to find the value of y(2)y(2).

More from this chapter

All Differential Equations solutions →

Solve your own maths question free →