lim cos2x - 1/cosx - 1
Evaluate : limx-0 cos2x -1/cosx-1
=limx-0 (2cos2x -1) -1/cosx-1
=limx-0 (2cos2x -2)/cosx-1
=limx-0 2{(cos2x -1)}/cosx-1
=limx-0 2 {(cosx -1)(cosx+1)} /cosx-1
=limx-0 2 {(cosx -1) (cosx+1)} /(cosx-1)
=limx-0 2 {(cosx +1)}
Applying the Limit :
=2 {(cos0 +1)}
=2 {(1 +1)}
=4
limh-0 cos2x -1/cosx-1 = 4