i can not understand how to integrate a power function like this one:
∫ (x² - 1) / (x³ - 3x + 1 ) ^ 6 dx
u multiplied by 1/3 to get rid of 3 ?in all of the solutions to these questions the author multiplied by a constant to get rid of a number, that what i can not understand why this multiplication is done and why we should get rid of the constant (3 for example)?