



 
Hi Peter, The fact that y varies jointly as x and the square of z and inversely as the cube of w means that
for some constant k. Suppose you input some values x = a, z = b and w = c. Then you obtain the output y = k ab^{2}/c^{3}. Now double the value of z and divide the value of w by 3. This means you are to input x = a, z = 2b and w = c/3. What is the output? How does it compare to the output you received for the inputs x = a, z = b and w = c? Harley  


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