A) 5
B) 20
C) 25
D) None of these
Correct Answer: C
Solution :
\[x+y=10;\]\[\therefore y=10-x\] ?..(i) Now \[f(x)=xy=x(10-x)=10x-{{x}^{2}}\] \[\therefore f'(x)=10-2x\] For maximum value of \[f(x),\,f'(x)=0\] \[\therefore x=5\] and \[y=5\] So maximum value of \[xy=5\times 5\,\,=25\].You need to login to perform this action.
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