max value of X

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max value of X

by Claret » Tue Jun 09, 2009 3:27 pm
If X^4+Y^4=100, then the greatest possible value of X is between:
A. 0 and 3
B. 3 and 6
C. 6 and 9
D. 9 and 12
E. 12 and 15

Ans B

IMO it shud be A

any insights?
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by ssmiles08 » Tue Jun 09, 2009 3:29 pm
If you make y = 0, to maximize x,
x will be a little bigger than 3 so it falls under [3 6]

(B)

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by Claret » Tue Jun 09, 2009 3:34 pm
yep got it ! thanks!