Answer:
y = 32
Explanation:
Given y is directly proportional to x² then the equation relating them is
y = kx² ← k is the constant of proportion
To find k use the condition when x = 3, y = 4.5 , then
4.5 = k × 3² = 9k ( divide both sides by 9 )
0.5 = k
y = 0.5x² ← equation of proportion
When x = 8 , then
y = 0.5 × 8² = 0.5 × 64 = 32