Solve the integral of x * e^(x^2 - 1) dx

Question image

Understand the Problem

The question requires us to evaluate the given indefinite integral. We need to find the antiderivative of the function x * e^(x^2 - 1) with respect to x. We will use u-substitution to solve this problem.

Answer

$\frac{1}{2}e^{x^2-1} + C$
Answer for screen readers

$\frac{1}{2}e^{x^2-1} + C$

Steps to Solve

  1. Perform u-substitution

Let $u = x^2 - 1$. Then, we need to find $du$. Taking the derivative of $u$ with respect to $x$, we have: $$ \frac{du}{dx} = 2x $$ Therefore $du = 2x , dx$.

  1. Rewrite the integral to incorporate the u-substitution

We have $x,dx$ in our integral, but we have $2x,dx$ in our expression for $du$. So, we rewrite the equation such that $$x,dx = \frac{1}{2} du$$ Now, we can rewrite the integral in terms of $u$: $$ \int xe^{x^2-1} dx = \int e^u \cdot \frac{1}{2} du = \frac{1}{2} \int e^u du $$

  1. Integrate with respect to u

The antiderivative of $e^u$ with respect to $u$ is simply $e^u$. So, we have: $$ \frac{1}{2} \int e^u du = \frac{1}{2} e^u + C $$

  1. Substitute back for x

Now we substitute $x^2 - 1$ back in for $u$: $$ \frac{1}{2} e^u + C = \frac{1}{2} e^{x^2 - 1} + C $$

$\frac{1}{2}e^{x^2-1} + C$

More Information

The indefinite integral of $ xe^{x^2-1} $ is $ \frac{1}{2}e^{x^2-1} + C $, where $ C $ is the constant of integration.

Tips

A common mistake is forgetting to include the constant of integration, $C$, when evaluating indefinite integrals. Another common mistake is not correctly solving for $dx$ in terms of $du$, or not substituting correctly back into the original variable.

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