limx→05x+3x+2x−3x
=limx→0(5x−1)+(3x−1)+(2x−1)x
=limx→05x−1x+limx→03x−1x+limx→02x−1x
=log 5+log 3+log 2
=log 30
limx→0sec5x−sec3xsec3x−secx
limx→05x−1√4+x−2