There are numbers A and B for which
A/(x - 1) + B/(x + 1) = (x + 8)/(x^2 - 1)
for every number $x\neq\pm1$. Find A-B
+309 Answer: 8
Solution:
Combining denominators on left, and then removing it from both sides gives
A(x+1) + B(x-1) = x + 8
Two equations can be found from this:
A + B = 1
A - B = 8
