>>4
Step 2: x^1(x^∞ - x^∞) =x^∞(x^∞ - x^∞)
if you took out x^∞ from the right side, you'd have x^∞(1-1), not x^∞(x^∞ - x^∞).
The only way you'd be able to get from step 2 to step 3 is if (x^∞ - x^∞) = (1-1)
Which means you divided by 0 going from step 2 to step 3.