∫3t·³√(2t²-1) dt
=3∫t·³√(2t²-1) dt
=3/4·∫³√(2t²-1) d(2t²-1)
=3/4×3/4×(2t²-1)^(3/4)+C
=9/16·(2t²-1)^(3/4)+C=3/4·∫³√(2t²-1) d(2t²-1)不明白t dt=1/4·d(2t²-1)这步清楚不