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Let \mathrm{A} be the area of the region \mathrm{\left\{(x, y): y \geq x^{2}, y \geq(1-x)^{2}, y \leq 2 x(1-x)\right\}}. Then 540 is equal to_____.

Option: 1

25


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer


\mathrm{x^{2}=(1-x)^{2} }               \mathrm{x^{2}=2 x-2 x^{2} }                 \mathrm{(1-x)^{2}+2 x-2 x^{2}}
\mathrm{x^{3}=1+x^{2}-2 x}       \mathrm{ 3 x^{1}=2 x}                            \mathrm{ 1+x^{2}-2 x=2 x-2 x^{2} }
  \mathrm{ x=\frac{1}{2} }                              \mathrm{ x(3 x-2)=0 }                  \mathrm{ \Rightarrow 3 x^{2}-4 x+1=0 }
\mathrm{ x=0, \frac{2}{3} }                            \mathrm{ \Rightarrow 3 x^{2}-3 x-x+1=0 }
                                             \mathrm{ \Rightarrow 3 x(x-1)-1(x-1)=0 }
                                              \mathrm{x=1, \frac{1}{3} }

Required Area
\mathrm{A=\int_{\frac{1}{3}}^{\frac{1}{2}}\left\{\left(2 x-2 x^{2}\right)-(1-x)^{2}\right\} d x+\int_{\frac{1}{2}}^{\frac{2}{3}}\left(\left(2 x-2 x^{2}\right)-x^{2}\right) d x}
\mathrm{\Rightarrow\left[x^{2}-\frac{2 x^{3}}{3}+\frac{(1-x)^{3}}{3}\right]_{\frac{1}{3}}^{\frac{1}{2}}+\left(x^{2}-x^{3}\right)_{1 / 2}^{2 / 3}}
\mathrm{\Rightarrow\left(\frac{1}{4}-\frac{2}{3} \cdot \frac{1}{8}+\frac{1}{8.3}\right)-\left(\frac{1}{9}-\frac{2}{3} \cdot \frac{1}{27}+\frac{8}{27.3}\right)+\left(\frac{4}{9}-\frac{8}{27}\right)-\left(\frac{1}{4}-\frac{1}{8}\right)}
\mathrm{\Rightarrow-\frac{1}{24}-\frac{1}{9}-\frac{6}{3 \times 27}+\frac{4}{9}-\frac{8}{27}+\frac{1}{8}}
\mathrm{\Rightarrow-\frac{1}{24}+\frac{3}{9}-\frac{10}{27}+\frac{3}{24}=\frac{-27+216-240+81}{24 \times 27}=\frac{297-267}{24 \times 27}=\mathrm{A}}
\mathrm{540 \mathrm{~A}=540 \times \frac{30}{24 \times 27}=25}
 

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Anam Khan

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