Answer :
Answer:To solve the problem, we can start by using the relationship that \( y \) varies directly as the square of \( x \). This relationship can be expressed as:
\[ y = kx^2 \]
where \( k \) is the constant of proportionality.
Given that \( y = 80 \) when \( x = 4 \), we can find the value of \( k \):
\[ 80 = k \cdot 4^2 \]
\[ 80 = k \cdot 16 \]
\[ k = \frac{80}{16} \]
\[ k = 5 \]
Now that we have the value of \( k \), we can use it to find \( x \) when \( y = 20 \):
\[ 20 = 5x^2 \]
\[ x^2 = \frac{20}{5} \]
\[ x^2 = 4 \]
\[ x = \sqrt{4} \]
\[ x = 2 \]
So, \( x = 2 \) when \( y = 20 \).
Step-by-step explanation:
