I'm having trouble understanding how two terms are to be factored out in an equation. By my textbook, I have...
(1+x2)2(-2x)-(1-x2)2(1+x2)(2x) / (1+x2)4
According to the textbook, I have to factor out like this
(1+x2)(2x) [(1+x2)(-1)-2(1-x2)] / (1+x2)4
Anyway, silly question, but how exactly am I supposed to factor out with both 1+x^2 and 2x? Any tips?