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Question-198806




Question Number 198806 by sonukgindia last updated on 24/Oct/23
Answered by Frix last updated on 24/Oct/23
∫((7x^2 +5)/(x^4 +6x^2 +25))dx=  =∫(((3x+1)/(2(x^2 −2x+5)))−((3x−1)/(2(x^2 +2x+5))))dx=  =∫((2/(x^2 −2x+5))+(2/(x^2 +2x+5))+((3(x−1))/(2(x^2 −2x+5)))−((3(x+1))/(2(x^2 +2x+5))))dx=  =tan^(−1)  ((x−1)/2) +tan^(−1)  ((x+1)/2) +((3ln (x^2 −2x+5))/4)−((3ln (x^2 +2x+5))/4)+C  ⇒ answer is π
$$\int\frac{\mathrm{7}{x}^{\mathrm{2}} +\mathrm{5}}{{x}^{\mathrm{4}} +\mathrm{6}{x}^{\mathrm{2}} +\mathrm{25}}{dx}= \\ $$$$=\int\left(\frac{\mathrm{3}{x}+\mathrm{1}}{\mathrm{2}\left({x}^{\mathrm{2}} −\mathrm{2}{x}+\mathrm{5}\right)}−\frac{\mathrm{3}{x}−\mathrm{1}}{\mathrm{2}\left({x}^{\mathrm{2}} +\mathrm{2}{x}+\mathrm{5}\right)}\right){dx}= \\ $$$$=\int\left(\frac{\mathrm{2}}{{x}^{\mathrm{2}} −\mathrm{2}{x}+\mathrm{5}}+\frac{\mathrm{2}}{{x}^{\mathrm{2}} +\mathrm{2}{x}+\mathrm{5}}+\frac{\mathrm{3}\left({x}−\mathrm{1}\right)}{\mathrm{2}\left({x}^{\mathrm{2}} −\mathrm{2}{x}+\mathrm{5}\right)}−\frac{\mathrm{3}\left({x}+\mathrm{1}\right)}{\mathrm{2}\left({x}^{\mathrm{2}} +\mathrm{2}{x}+\mathrm{5}\right)}\right){dx}= \\ $$$$=\mathrm{tan}^{−\mathrm{1}} \:\frac{{x}−\mathrm{1}}{\mathrm{2}}\:+\mathrm{tan}^{−\mathrm{1}} \:\frac{{x}+\mathrm{1}}{\mathrm{2}}\:+\frac{\mathrm{3ln}\:\left({x}^{\mathrm{2}} −\mathrm{2}{x}+\mathrm{5}\right)}{\mathrm{4}}−\frac{\mathrm{3ln}\:\left({x}^{\mathrm{2}} +\mathrm{2}{x}+\mathrm{5}\right)}{\mathrm{4}}+{C} \\ $$$$\Rightarrow\:\mathrm{answer}\:\mathrm{is}\:\pi \\ $$

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