Answer:
Step-by-step explanation:
When two quantities are directly proportional, an increase in one quantity results to a corresponding in the other quantity.
Given that Z is jointly proportional to x² and y², if we introduce a constant of proportionality, k, the expression becomes
z = kx²y²
If z = 379 when x = 7 and y = 5, then
379 = k × 7² × 5² = 1225
k = 379/1225
Therefore, the joint proportionality function is
z = 379x²y²/1225
when x = 6 and y = 4, then
z = 379 × 6² × 4²/1225
z = 218304/1225
z = 178.2
