A) limx→∞f(x)=limx→∞3√(x+1)2−3√(x−1)2=limx→∞(x+1)2−(x−1)2(x+1)4/3+(x−1)4/3+(x2−1)2/3
=limx→∞4x−1/3(1+x−1)4/3+(1−x−1)4/3+(1−x−2)2/3=01+1+1=0
B) limx→∞f(x)=limx→∞x3/2(√x3+1−√x3−1)=limx→∞2x3/2√x3+1+√x3−1
=limx→∞2x3/21−√x−3+√1−x−3=1
C) limx→∞f(x)=limx→∞(√x2−2x−1−√x2−7x+3)=limx→∞5x−4√x2−2x−1−√x2−7x+3
=limx→∞5−4/x√1−2/x−1+√1−7/x+3/x2=52
D) limx→∞f(x)=limx→∞√(x+1)(x+2)−x=limx→∞3x+2√(x+1)(x+2)+x
=limx→∞3+2/x√(1+x−1)(1+2x−1)+1=32