[tex] \sqrt{72} + \sqrt{162} \\ \\ \sqrt{2 \times 2 \times 2 \times 3 \times 3} + \sqrt{2 \times 3 \times 3 \times 3 \times 3} \\ \\ 2 \times 3 \sqrt{2} + 3 \times 3 \sqrt{2} \\ \\ 6 \sqrt{2} + 9 \sqrt{2} \\ \\ (6 + 9) \sqrt{2} \\ \\ 15\times1.4 \\ \\ 21[/tex]
[tex] \sqrt{50} - \sqrt{8} \\ \\ \sqrt{2 \times 5 \times 5} - \sqrt{2 \times 2 \times 2} \\ \\ 5 \sqrt{2} - 2\sqrt{2} \\ \\ (5 - 2) \sqrt{2} \\ \\ 3 \sqrt{2} \\ \\ 1.7 \times 2 \\ \\ 3.4[/tex]
[tex]2 \sqrt{28} + \sqrt{28} \\ \\ 2 \sqrt{2 \times 7 \times 7} + \sqrt{2 \times 7 \times 7} \\ \\ 2 \times 7 \sqrt{2} + 7 \sqrt{2} \\ \\ 14 \sqrt{2} + 7 \sqrt{2} \\ \\ (14 + 7) \sqrt{2} \\ \\ 21 \times 1.4 \\ \\ 29.4[/tex]
