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int(2x^(3)-4x-8)/((x^(2)-x)(x^(2)+4))dx

11. 2x34x8(x2x)(x2+4)dx \int \frac{2 x^{3}-4 x-8}{\left(x^{2}-x\right)\left(x^{2}+4\right)} d x

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Q. 11. 2x34x8(x2x)(x2+4)dx \int \frac{2 x^{3}-4 x-8}{\left(x^{2}-x\right)\left(x^{2}+4\right)} d x
  1. Rewrite Integral: Rewrite the integral by factoring the denominator and simplifying the expression.\newlineDenominator: (x2x)(x2+4)=x(x1)(x2+4)(x^2 - x)(x^2 + 4) = x(x - 1)(x^2 + 4).\newlineAttempt partial fraction decomposition:\newlineLet 2x34x8x(x1)(x2+4)=Ax+Bx1+Cx+Dx2+4\frac{2x^3 - 4x - 8}{x(x - 1)(x^2 + 4)} = \frac{A}{x} + \frac{B}{x - 1} + \frac{Cx + D}{x^2 + 4}.\newlineMultiply through by the denominator to clear fractions:\newline2x34x8=A(x1)(x2+4)+Bx(x2+4)+(Cx+D)x(x1)2x^3 - 4x - 8 = A(x - 1)(x^2 + 4) + Bx(x^2 + 4) + (Cx + D)x(x - 1).
  2. Partial Fraction Decomposition: Expand and equate coefficients for x3x^3, x2x^2, xx, and constant terms.\newlineExpanding:\newlineA(x3x2+4x4)+B(x3+4x)+Cx2(x1)+Dx(x1)A(x^3 - x^2 + 4x - 4) + B(x^3 + 4x) + Cx^2(x - 1) + Dx(x - 1)\newline= Ax3Ax2+4Ax4A+Bx3+4Bx+Cx3Cx2+Dx2DxAx^3 - Ax^2 + 4Ax - 4A + Bx^3 + 4Bx + Cx^3 - Cx^2 + Dx^2 - Dx.\newlineCombine like terms and equate to the original polynomial:\newline(A+B+C)x3+(AC+D)x2+(4A+4BD)x4A=2x34x8(A + B + C)x^3 + (-A - C + D)x^2 + (4A + 4B - D)x - 4A = 2x^3 - 4x - 8.
  3. Expand and Equate Coefficients: Solve the system of equations for AA, BB, CC, DD:\newline11. A+B+C=2A + B + C = 2,\newline22. AC+D=0-A - C + D = 0,\newline33. 4A+4BD=44A + 4B - D = -4,\newline44. 4A=8-4A = -8.\newlineFrom equation 44, A=2A = 2.\newlineSubstitute AA into other equations and solve for BB, CC, DD.
  4. Solve System of Equations: Substituting A=2A = 2 into equations:\newline11. 2+B+C=22 + B + C = 2, B+C=0B + C = 0,\newline22. 2C+D=0-2 - C + D = 0, D=2+CD = 2 + C,\newline33. 8+4BD=48 + 4B - D = -4.\newlineSubstitute D=2+CD = 2 + C into equation 33:\newline8+4B(2+C)=48 + 4B - (2 + C) = -4,\newline4BC=104B - C = -10.
  5. Solve for BB and CC: Solve B+C=0B + C = 0 and 4BC=104B - C = -10 simultaneously:\newlineFrom B+C=0B + C = 0, C=BC = -B.\newlineSubstitute C=BC = -B into 4BC=104B - C = -10:\newline4B+B=104B + B = -10,\newline5B=105B = -10,\newlineCC00.\newlineThen CC11.
  6. Find D: Find D using D=2+CD = 2 + C: D=2+2=4D = 2 + 2 = 4. Now we have A=2A = 2, B=2B = -2, C=2C = 2, D=4D = 4. The partial fractions are: 2x2x1+2x+4x2+4\frac{2}{x} - \frac{2}{x - 1} + \frac{2x + 4}{x^2 + 4}.
  7. Integrate Each Term: Integrate each term separately:\newline2xdx=2lnx+C1,\int \frac{2}{x} dx = 2 \ln|x| + C_1,\newline2x1dx=2lnx1+C2,\int \frac{-2}{x - 1} dx = -2 \ln|x - 1| + C_2,\newline2x+4x2+4dx=ln(x2+4)+4arctan(x2)+C3.\int \frac{2x + 4}{x^2 + 4} dx = \ln(x^2 + 4) + 4 \arctan\left(\frac{x}{2}\right) + C_3.\newlineCombine constants: C=C1+C2+C3.C = C_1 + C_2 + C_3.