SOLUTION: A variable a varies jointly as b and the square of c and inversely as d. When a= -14, b=5, c=8, and d=20. Write the equation to represent this variation. Then find a when b=4, c=6,

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Question 620191: A variable a varies jointly as b and the square of c and inversely as d. When a= -14, b=5, c=8, and d=20. Write the equation to represent this variation. Then find a when b=4, c=6, and d=9.
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
Let the variable be a
You are told
a+=+K+%28bc%5E2%29%2Fd
now plug in the values of a= -14, b=5, c=8, and d=20
and solve for K
-14+=+K+%285%2A8%5E2%29%2F20
-14+=+K+%2864%2F4%29
-14%2F16+=+K
Plug in K
a+=+%28-14%2F16%29%2A%28bc%5E2%29%2Fd
now plug in b=4, c=6, and d=9 and solve for a
a+=%28-14%2F16%29%2A%284%2A6%5E2%29%2F9