Răspuns:
[tex]5 - \sqrt{72} - (4 + 5 \sqrt{2} - (98 - 20)) = 5 - \sqrt{9 \times 8} - (4 + 5 \sqrt{2} - 78) = \\ = 5 - \sqrt{9} \times \sqrt{8} - 4 - 5 \sqrt{2} + 78 = \\ = 5 - 3 \times \sqrt{4 \times 2} - 4 - 5 \sqrt{2} + 78 = \\ = 5 - 3 \times \sqrt{4} \times \sqrt{2} - 4 - 5 \sqrt{2} + 78 = \\ = 5 - 3 \times 2 \times \sqrt{2} - 4 - 5 \sqrt{2} + 78 = \\ = 5 - 6 \sqrt{2} - 4 - 5 \sqrt{2} + 78 = \\ = 5 - 4 + 78 - 6 \sqrt{2} - 5 \sqrt{2} = \\ = 79 - 11 \sqrt{2} [/tex]
