1.

Let `x`be the arithmetic mean and `y ,z`be tow geometric means between any two positive numbers. Then, prove that`(y^3+z^3)/(x y z)=2.`

Answer» Let `a` and `b` are two positive numbers.
Then,
`x = (a+b)/2`
`y^2 = az and z^2 = yb`
`=>y^3 = ayz and z^3 = byz`
Now, `(y^3+z^3)/(xyz) = (ayz+byz)/(((a+b)/2)yz)`
`=2((a+b)yz)/((a+b)yz) =2`
`:. (y^3+z^3)/(xyz) = 2.`


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