Evaluate: `int(x-1)sqrt(1+x+x^(2))`dx

Explanation

To evaluate the integral \( \int (x-1) \sqrt{1+x+x^2} \, dx \), we can follow these steps:

### Step 1: Rewrite the Integral
We start with the integral:
\[ I = \int (x-1) \sqrt{1+x+x^2} \, dx \]

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