Yeah bro,ofcourse! You must be knowing why did you fail in that subject such as poor english skill or couldnt revise and practice derivations etc.jee main is a different game ,where you are expected to be good in numericals,shortcuts etc.if you feel there doesnt lie any problem in it,fill the form ofcourse.btw if sub you failed is other than pcm,then dont ever be in doubt of your jee main capability .plzz rectify your problem time is in hand