✔ 最佳答案
2x * dx / (2 + x - x^2)
-2x * dx / (x^2 - x - 2)
x^2 - x - 2 = 0
x = (1 +/- sqrt(1 + 8)) / 2
x = (1 +/- 3) / 2
x = -2/2 , 4/2
x = -1 , 2
x + 1 , x - 2 = 0
-2x / ((x + 1) * (x - 2))
A/(x + 1) + B/(x - 2) = (-2x + 0) / ((x + 1) * (x - 2))
A * (x - 2) + B * (x + 1) = -2x + 0
Ax + Bx - 2A + B = -2x + 0
A + B = -2
-2A + B = 0
2 * (A + B) - 2A + B = 2 * (-2) + 0
2A - 2A + 2B + B = -4
3B = -4
B = -4/3
A + B = -2
A - 4/3 = -6/3
A = -2/3
(-2/3) * dx / (x + 1) - (4/3) * dx / (x - 2) =>
(-2/3) * (dx / (x + 1) + 2 * dx / (x - 2))
Integrate
(-2/3) * (ln|x + 1| + 2 * ln|x - 2|) + C
(-2/3) * ln|(x + 1) * (x - 2)^2| + C