Explanation
the properties of exponents
[tex]\begin{gathered} \sqrt[n]{a}=a^{\frac{1}{n}} \\ \sqrt[n]{a^{n^{}}b^n}\text{ = ab} \\ \sqrt[]{ab}=\sqrt[]{a}\cdot\sqrt[]{b} \end{gathered}[/tex]
Step 1
Zoe believes
[tex]\sqrt[]{2}+\sqrt[]{8\text{ }}=\text{ 2.21}[/tex]
Marsden Believes
[tex]\sqrt[]{2}+\sqrt[]{8}=3.21[/tex]
Step 2
[tex]\sqrt[]{8}=\sqrt[]{4}\cdot\sqrt[]{2}=\text{ 2}\sqrt[]{2}[/tex]
then
[tex]\begin{gathered} \sqrt[]{2}+\sqrt[]{8}=\text{ }\sqrt[]{2}+2\sqrt[]{2}=3\sqrt[]{2} \\ \text{also } \\ \sqrt[]{2}=\text{ 1.4142} \\ so, \\ \sqrt[]{2}+\sqrt[]{8}=3\sqrt[]{2}=3\cdot1.4142=4.24 \end{gathered}[/tex]
then
[tex]\sqrt[]{2}+\sqrt[]{8}=3\sqrt[]{2}=3\cdot1.4142=4.24[/tex]
I hope this helps you