Error

Target

Derivation

1. Initial program 9.8

   \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
2. Using strategy rm

3. Applied frac-sub25.6

   \[\leadsto \color{blue}{\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x}} + \frac{1}{x - 1}\]

4. Applied frac-add24.8

   \[\leadsto \color{blue}{\frac{\left(1 \cdot x - \left(x + 1\right) \cdot 2\right) \cdot \left(x - 1\right) + \left(\left(x + 1\right) \cdot x\right) \cdot 1}{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}}\]

5. Taylor expanded around -inf 0.3

   \[\leadsto \frac{\color{blue}{2}}{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}\]
6. Using strategy rm

7. Applied associate-/r*0.1

   \[\leadsto \color{blue}{\frac{\frac{2}{\left(x + 1\right) \cdot x}}{x - 1}}\]

8. Taylor expanded around inf 0.1

   \[\leadsto \frac{\frac{2}{\color{blue}{x + {x}^{2}}}}{x - 1}\]

9. Simplified0.1

   \[\leadsto \frac{\frac{2}{\color{blue}{x + x \cdot x}}}{x - 1}\]

10. Final simplification0.1

    \[\leadsto \frac{\frac{2}{x + x \cdot x}}{x - 1}\]

Reproduce

herbie shell --seed 2019091 
(FPCore (x)
  :name "3frac (problem 3.3.3)"

  :herbie-target
  (/ 2 (* x (- (* x x) 1)))

  (+ (- (/ 1 (+ x 1)) (/ 2 x)) (/ 1 (- x 1))))