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If `y z+z x+x y=12 ,w h e r ex ,y ,z`are positive values, find the greatest value of `x y zdot` |
Answer» Given, `yz+zx+xy=12` (constant), the value of `(yz)(zx)(xy)` is greatest when `yz=zx=xy` Hence, `n=3` and `k=12` Hence, greatest value of `(yz)(zx)(xy)` is `((12)/(3))^(3)` i.e.64. `:.` Greatest value of `x^(2)y^(2)z^(2)` is 64. Thus, greatest value of xyz is 8. Aliter Given `yz+zx+xy=12`, the greatest value of (yz)(zx)(xy) is greatest when `yz=zx=xy=c " " [" say "]` Since, `yz+zx+xy=12` `:. c+c+c=12` `implies 3c=12` r `c=4` `:. yz=zx=xy=4` Hence, greatest value of (yz)(zx)(xy) is `4*4*4` i.e. greatest value of `x^(2)y^(2)z^(2)` is 64. Hence, greatest value of xyz is 8. |
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