Answer:
see explanation
Step-by-step explanation:
(1)
y varies directly as x² then the equation relating them is
y = kx² ← k is the constant of variation
To find k use the condition y = 32 when x = 2
32 = k × 2² = 4k ( divide both sides by 4 )
8 = k
y = 8x² ← equation of variation
When x = 5 , then
y = 8 × 5² = 8 × 25 = 200
(2)
Given F varies inversely as d² then the equation relating them is
F = ← k is the constant of variation
To find k use the condition F = 18 when d = 10
18 = =
( multiply both sides by 100 )
1800 = k
F = ← equation of variation
When d = 15 , then
F = =
= 8
(3)
y varies jointly as x and z then the equation relating them is
y = kxz ← k is the constant of variation
when x = 3, y = 6, z = 9 ,then
y = 6 × 3 × 9 = 162