Question

S={} T={x|x is a number satisfying x^2 + 4 =0} Determine if Equal,Equivalent,Subset or None of the above.

Answer 1

what type of number?

Answer 2

you have two sets S and T
S is empty for sure
how about T ?

Answer 3

T={x|x is a number satisfying x^2 + 4 =0}

Answer 4

ok that is why @amistre64 asked the question he did
if your universal set is all real numbers, then T is empty as well, since there is no real number that satisfies \(x^2=-4\)