Question

I have two different answers

Answer 1

If two roots have the same index, you can multiply their content:

`\sqrt[3]{a}\cdot \sqrt[3]{b}=\sqrt[3]{ab}`

So, you have

`\sqrt[3]{9x}\cdot\sqrt[3]{49x}=\sqrt[3]{9x\cdot 49x}=\sqrt[3]{441x^2}`