3. Given $\sqrt{x^{2}+32}-\sqrt{65-x^{2}}=5$. Then $3 \sqrt{x^{2}+32}+2 \sqrt{65-x^{2}}=$ $\qquad$
3.35.

Observing the experiment, we know that $x^{2}=49$, so the original expression $=3 \times 9+2 \times 4=35$.