Math Problem Statement

Resolve in partial fraction

Solution

The expression in the image is:

11x24(x2+2)(x2+3)\frac{11x^2 - 4}{(x^2 + 2)(x^2 + 3)}

We want to resolve this expression into partial fractions. Given that the denominator consists of two irreducible quadratic factors, the partial fraction decomposition will have the form:

11x24(x2+2)(x2+3)=Ax+Bx2+2+Cx+Dx2+3\frac{11x^2 - 4}{(x^2 + 2)(x^2 + 3)} = \frac{Ax + B}{x^2 + 2} + \frac{Cx + D}{x^2 + 3}

Step 1: Combine the fractions on the right-hand side

To combine the fractions, get a common denominator:

Ax+Bx2+2+Cx+Dx2+3=(Ax+B)(x2+3)+(Cx+D)(x2+2)(x2+2)(x2+3)\frac{Ax + B}{x^2 + 2} + \frac{Cx + D}{x^2 + 3} = \frac{(Ax + B)(x^2 + 3) + (Cx + D)(x^2 + 2)}{(x^2 + 2)(x^2 + 3)}

Step 2: Set the numerators equal

Since the denominators are the same, equate the numerators:

11x24=(Ax+B)(x2+3)+(Cx+D)(x2+2)11x^2 - 4 = (Ax + B)(x^2 + 3) + (Cx + D)(x^2 + 2)

Step 3: Expand and collect like terms

Expanding the right-hand side:

(Ax+B)(x2+3)=Ax3+3Ax+Bx2+3B(Ax + B)(x^2 + 3) = Ax^3 + 3Ax + Bx^2 + 3B (Cx+D)(x2+2)=Cx3+2Cx+Dx2+2D(Cx + D)(x^2 + 2) = Cx^3 + 2Cx + Dx^2 + 2D

Combining these:

Ax3+Bx2+3Ax+3B+Cx3+Dx2+2Cx+2DAx^3 + Bx^2 + 3Ax + 3B + Cx^3 + Dx^2 + 2Cx + 2D =(A+C)x3+(B+D)x2+(3A+2C)x+(3B+2D)= (A + C)x^3 + (B + D)x^2 + (3A + 2C)x + (3B + 2D)

Step 4: Match coefficients

Now, match the coefficients of corresponding powers of xx:

For x3x^3 terms: A+C=0A + C = 0

For x2x^2 terms: B+D=11B + D = 11

For xx terms: 3A+2C=03A + 2C = 0

For the constant term: 3B+2D=43B + 2D = -4

Step 5: Solve the system of equations

From A+C=0A + C = 0, we have: C=AC = -A

Substituting C=AC = -A into 3A+2C=03A + 2C = 0, we get: 3A+2(A)=3A2A=A=03A + 2(-A) = 3A - 2A = A = 0

Since A=0A = 0, C=A=0C = -A = 0.

Now, using B+D=11B + D = 11 and 3B+2D=43B + 2D = -4:

Substitute D=11BD = 11 - B into 3B+2D=43B + 2D = -4: 3B+2(11B)=43B + 2(11 - B) = -4 3B+222B=43B + 22 - 2B = -4 B+22=4B + 22 = -4 B=26B = -26

Then, using D=11BD = 11 - B: D=11(26)=11+26=37D = 11 - (-26) = 11 + 26 = 37

Step 6: Write the partial fraction decomposition

The partial fraction decomposition is:

11x24(x2+2)(x2+3)=26x2+2+37x2+3\frac{11x^2 - 4}{(x^2 + 2)(x^2 + 3)} = \frac{-26}{x^2 + 2} + \frac{37}{x^2 + 3}

Would you like more details or have any questions?

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