F(t)=2t−3f, left parenthesis, t, right parenthesis, equals, 2, t, minus, 3 f(7)=f(7)=f, left parenthesis, 7, right parenthesis, equals

Consider u = {x|x is a negative real number}which is an empty set? o {x|x eu and x has a negative cube root}o {x|x eu and x has a negative square root}{x|x eu and x is equal to the product of a positive number and -1}{x|x eu and x is equal to the sum of one negative and one positive number?