To vertically stretch a function by a factor of 4, you multiply the entire function by 4. The original function given is:
\[ y = \sqrt[3]{x^2} \]
To vertically stretch this function by a factor of 4, you apply the transformation:
\[ y = 4 \cdot \sqrt[3]{x^2} \]
This means the transformed equation is:
\[ y = 4 \sqrt[3]{x^2} \]
Now let's look at the options provided:
- \( y = \sqrt[3]{4x^2} \)
- \( y = \sqrt[3]{x^8} \)
- \( y = \sqrt[3]{(4x)^2} \)
- \( y = 4 \sqrt[3]{x^2} \)
The correct transformed equation corresponding to a vertical stretch by a factor of 4 is:
\[ y = 4 \sqrt[3]{x^2} \]
So the answer is:
\[ \boxed{y = 4 \sqrt[3]{x^2}} \]