The roots of the equation $x^2 + 5x - 7 = 0$ are $x_1$ and $x_2$. Find the value of $x_1^3 + 5x_1^2 - 4x_1 + x_1^2 x_2 - 4x_2$.

Let's think step by step and output the final answer within \boxed{}.
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