Question 1186155: Suppose z varies directly with x and inversely with the square of y. If z=12 when x=4 and y=4, what is z when x=8 and y=10?
Found 3 solutions by Theo, MathTherapy, ikleyn:
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! direct variation equation is y = k * x
solve for k to get k = y/x.
inverse variation equation is y = k/x
solve for k to get k = y * x.
when you are dealing with direct and inverse relationships, the equation is z = k * x / y
x is the direct variation variable and y is the inverse variation variable.
when z = 12 and x = 4 and y = 4, the equation becomes:
12 = k * 4 / 4 which becomes:
12 = k
now that you know the value of k, you can solve the problem, because k is the constant of variation and doesn't change.
when x = 8 and y = 10, z = k * x / y becomes z = 12 * 8 / 10 which becomes z = 9.6.
that's your solution.
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website!
Suppose z varies directly with x and inversely with the square of y. If z=12 when x=4 and y=4, what is z when x=8 and y=10?
He's WRONG!!
When x = 8 and y = 10, 
Answer by ikleyn(52797)  (Show Source):
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