" 7.सिद्ध Do it "A sub phi rArr A=phi

Prove that A sub phi rArr A=phi

Prove that A sub phi implies A =phi .

Prove that : phi- A= phi .

Determine if A sub B or A cancel sub B where A=phi, B ={phi}

Determine the truth of falsity of the A sub phi "if and only if "A = phi propositions with reasons.

In a binary operation **: phi xx phi rarr phi is defined as a ** b = (ab)/4, a , b in phi . Show that ** is associative.

tan phi cos ec phi=sec phi

IF A= {6,9,11},phi={} , find A cup phi, A cap phi .