1.

\f1 1 If u = = + 1, then dx - du. 2 + 12x If u = a2+ 1, then dx = - du. x2 + 1 u3 1 3 1 A. / d3: : f tin (with the substitution u : a: i 1) 2 :13 + 1 2 u 3 2 1 1 B. / d2: : f do (with the substitution u : :1: + 1) 2 :c + 1 1 u 3 4 1 1 (3. da: : dot (with the substitution u : :13 + 1) 2 3 U 2 1 3 1 D. / d2: : f du (with the substitution u : :1: + 1) 1 a: + 1 2 u E. None of the above