2. Let

$$
\sqrt{49-a^{2}}-\sqrt{25-a^{2}}=3
$$

Calculate the value of the expression

$$
\sqrt{49-a^{2}}+\sqrt{25-a^{2}} .
$$
Answer: 8.

Solution. Let

$$
\sqrt{49-a^{2}}+\sqrt{25-a^{2}}=x
$$

Multiplying this equality by the original one, we get $24=3x$.

Evaluation. Full solution: 11 points.