SOLUTION: 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?

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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(52803)   (Show Source): You can put this solution on YOUR website!
 .



    z' =  =  =  = .    ANSWER





 

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