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Let f(x) =`xsqrt(4ax-x^(2)),(agt0)` Then f(x) isA. increasing in (0,3a) decreasing in (3a,4a)B. increasing in (a,4a),decreasing in `(5a,oo)`C. increasing in `(0,4a)`D. none of these |
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Answer» Correct Answer - 1 f(X)=`xsqrt(4ax-x^(2))` `therefore f(X) =sqrt(4ax-x^(2))+x(4a-2x)/2sqrt(4ax-x^(2))` `=(2x(3a-x))/sqrt(4ax-x^(2))` Now if `f(X)gt0` then `2x(3a-x)gt0` `2x(x-3a)lt0` or x in (0,3a) Thus f(x) increases in (0,3a) and decreases in (3a,4a) Thus f(X) increases in (0,3a) and decreases (3a,4a) |
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