Question

please solve 2nd one

Answer 1

Hope this helps you.

Answer 2

$16 = 2 \times 2 \times 2 \times 2 = {2}^{4} \\ \sqrt{16} = \sqrt{ {2}^{4} } = {2}^{2} = 4$

$343 = 7 \times 7 \times 7 = {7}^{3} \\ \sqrt{343} = \sqrt{ {7}^{3} } = 7 \sqrt{7}$

$243 = 3 \times 3 \times 3 \times 3 \times 3 = {3}^{5} \\ \sqrt[3]{243} = \sqrt[3]{ {3}^{5} } = 3 \sqrt[3]{ {3}^{2} } = 3 \sqrt[3]{9}$

$196 = 2 \times 2 \times 7 \times 7 = {2}^{2} \times {7}^{2} \\ \sqrt{196} = \sqrt{ {2}^{2} \times {7}^{2} } = 2 \times 7 = 14$


$4 \sqrt{16} - 6 \sqrt[2]{343} + 18 \sqrt[3]{243} - \sqrt{196} \\ \\ = 4 \times 4 - 6 \times 7 \sqrt{7} + 18 \times 3 \sqrt[3]{9} - 14 \\ \\ = 16 - 42 \sqrt{7} + 54 \sqrt[3]{9} - 14 \\ \\ = 2- 42 \sqrt{7} + 54 \sqrt[3]{9}$

You should keep it at that point.

If you want a final answer,

$2- 42 \sqrt{7} + 54 \sqrt[3]{9} \\ \\ = 2 - 111.122 + 112.325 \\ \\ = 3.203$