How do you integrate (2x-3)/(x^2-5x+6)2x3x25x+6 using partial fractions?

1 Answer
Dec 3, 2016

Please see the explanation.

Explanation:

Do partial fraction decomposition:

(2x - 3)/((x - 2)(x - 3)) = A/(x - 2) + B/(x - 3)2x3(x2)(x3)=Ax2+Bx3

Multiply both sides by ((x - 2)(x - 3))((x2)(x3))

(2x - 3) = A(x - 3) + B(x - 2)(2x3)=A(x3)+B(x2)

Solve for A by letting x = 2x=2:

(2(2) - 3) = A(2 - 3)(2(2)3)=A(23)

-1 = A1=A

Solve for B by letting x = 3x=3:

(2(3) - 3) = B(3 - 2)(2(3)3)=B(32)

3 = B

Check:

-1/(x - 2) + 3/(x - 3) = 1x2+3x3=

-1/(x - 2)(x - 3)/(x - 3) + 3/(x - 3)(x - 2)/(x - 2) =1x2x3x3+3x3x2x2=

(-x + 3)/((x - 2)(x - 3)) + (3x - 6)/((x - 3)(x - 2)) =x+3(x2)(x3)+3x6(x3)(x2)=

(2x - 3)/((x - 3)(x - 2))2x3(x3)(x2)

This checks.

int (2x - 3)/(x^2 - 5x + 6)dx = 3int 1/(x - 3)dx - int1/(x - 2)dx2x3x25x+6dx=31x3dx1x2dx

int (2x - 3)/(x^2 - 5x + 6)dx = 3ln|x - 3| - ln|x - 2| + C2x3x25x+6dx=3ln|x3|ln|x2|+C