Factor $32=4^{2}\times 2$. Rewrite the square root of the product $\sqrt{4^{2}\times 2}$ as the product of square roots $\sqrt{4^{2}}\sqrt{2}$. Take the square root of $4^{2}$.
$$-4\sqrt{2}+\sqrt{72}-\sqrt{50}$$
Factor $72=6^{2}\times 2$. Rewrite the square root of the product $\sqrt{6^{2}\times 2}$ as the product of square roots $\sqrt{6^{2}}\sqrt{2}$. Take the square root of $6^{2}$.
$$-4\sqrt{2}+6\sqrt{2}-\sqrt{50}$$
Factor $50=5^{2}\times 2$. Rewrite the square root of the product $\sqrt{5^{2}\times 2}$ as the product of square roots $\sqrt{5^{2}}\sqrt{2}$. Take the square root of $5^{2}$.
$$-4\sqrt{2}+6\sqrt{2}-5\sqrt{2}$$
Combine $6\sqrt{2}$ and $-5\sqrt{2}$ to get $\sqrt{2}$.
$$-4\sqrt{2}+\sqrt{2}$$
Combine $-4\sqrt{2}$ and $\sqrt{2}$ to get $-3\sqrt{2}$.
