5-4. Solve the inequality

$$
\sqrt{10 x-21}-\sqrt{5 x^{2}-21 x+21} \geqslant 5 x^{2}-31 x+42
$$

In your answer, indicate the sum of all integer values of $x$ that satisfy the inequality.
Solution. The inequality is satisfied only by the following integer values: $x=3, x=4$.

Answer: (D) 7.

Answer choices.

![](https://cdn.mathpix.com/cropped/2024_05_06_997c53c06135e2de9c16g-05.jpg?height=65&width=633&top_left_y=2052&top_left_x=763)