Explicație pas cu pas:
3.
[tex]3 \sqrt{18} = 3 \times 3 \sqrt{2} = 9 \sqrt{2} \\ 4\sqrt{32} = 4 \times 4 \sqrt{2} = 16 \sqrt{2} \\ 9 \sqrt{2} + 16 \sqrt{2} = 25 \sqrt{2} [/tex]
[tex](1 - \sqrt{7} )(1 + \sqrt{7} ) - ( \sqrt{7} + \sqrt{14} ) ^{2} = \\ (1^{2} - \sqrt{7}^{2} )- \sqrt{7} ^{2} + 2 \times \sqrt{7} \times \sqrt{14} \times \sqrt{14} = \\ (1 - 7) - 7 + 2 \times \sqrt{98} \ + 14 \\ = - 7 - 14 \sqrt{2} + 1 = - 6 - 14 \sqrt{2} [/tex]
4.
[tex]3 + \sqrt{17} + 4.8 + \sqrt{17} = \\ 7.8 + \sqrt{17} = 8 + \sqrt{17} [/tex]
