A) 8
B) 16
C) 20
D) 24
Correct Answer: B
Solution :
\[x+y=8;\]\[\therefore y=8-x\] .....(i) Now \[f(x)=xy=x(8-x)=8x-{{x}^{2}}\], \[\therefore {f}'(x)=8-2x\] For maximum value of \[f(x),\,f'(x)=0\] \[\therefore \] \[x=4\] and \[y=4\] So, maximum value of \[xy=4\times 4=16\].You need to login to perform this action.
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