Problem

5x4+7x2+x+2x(x2+1)2dx

Answer

Expert–verified
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Answer

\boxed{\int \frac{5 x^{4}+7 x^{2}+x+2}{x\left(x^{2}+1\right)^{2}} d x = 5\ln|x| + \frac{9}{2} \ln(x^2 + 1) - \frac{1}{2(x^2 + 1)} + C}\)

Steps

Step 1 :5x4+7x2+x+2x(x2+1)2dx=Ax+Bx+Cx2+1+Dx+E(x2+1)2dx

Step 2 :5x4+7x2+x+2=A(x2+1)2+(Bx+C)x(x2+1)+(Dx+E)x

Step 3 :5x4+7x2+x+2=Ax4+2Ax2+A+Bx3+Bx+Cx2+C+Dx3+Dx+Ex2+E

Step 4 :A=5,B+D=0,2A+B+C+E=7,C+E=1,B+D=1

Step 5 :A=5,B=D,C=1E,2(5)D+1E+E=7

Step 6 :D=3,B=3,C=1E,E=1

Step 7 :5x4+7x2+x+2x(x2+1)2dx=5x+3x3x2+1+3x+1(x2+1)2dx

Step 8 :5x4+7x2+x+2x(x2+1)2dx=51xdx+3x1x2+1dx3x13(x2+1)2dx

Step 9 :5x4+7x2+x+2x(x2+1)2dx=5ln|x|+3ln(x2+1)3x13(x2+1)2dx

Step 10 :u=x2+1,du=2xdx

Step 11 :32u13u2du=321udu+121u2du

Step 12 :321udu+121u2du=32ln|u|+12u+C

Step 13 :32ln|x2+1|+12(x2+1)+C=32ln(x2+1)+12(x2+1)+C

Step 14 :5x4+7x2+x+2x(x2+1)2dx=5ln|x|+3ln(x2+1)(32ln(x2+1)+12(x2+1)+C)

Step 15 :5x4+7x2+x+2x(x2+1)2dx=5ln|x|+92ln(x2+1)12(x2+1)+C

Step 16 :\boxed{\int \frac{5 x^{4}+7 x^{2}+x+2}{x\left(x^{2}+1\right)^{2}} d x = 5\ln|x| + \frac{9}{2} \ln(x^2 + 1) - \frac{1}{2(x^2 + 1)} + C}\)

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