Monday, March 3, 2014

`y = x^2e^x` Determine whether this function is a solution of the differential equation `xy' - 2y = x^3e^x`.

To determine whether the given function is a solution of the given differential equation, we can find the derivative of the function and check if it satisfies the equation.


To find the derivative of `y = x^2e^x` , use the product rule:


`(fg)' = f'g + fg'`


Here, `f = x^2` and `f' = 2x` , and `g = e^x ` and `g' = e^x` .


So `y' = 2xe^x + x^2e^x = x(2 + x)e^x` .


The left-hand side of the given equation will then be


`xy' - 2y =2x^2e^x + x^3e^x- 2x^2e^x = x^3e^x` . This is exactly the same as the right-hand side of the given equation, which means `y(x) = x^2e^x` is a solution.


The function `y(x) = x^2e^x` is a solution of the given differential equation.

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