Question

Determine if the biconditional statements are true or false.

1. Any whole number is divisible by 3 if and only if the sum of its digits is divisible by 3.
2. 1/x > 0 if and only if x ≥ 0.
3. 2 is a prime if and only if 7 is even.

Answer 1

1. yes --- https://www.apronus.com/math/threediv.htm
2. no try x = 0.5
3. makes no sense to me

Answer 2

in number 2, if you try it with 0.5 then 2 > 0 and 0.5 ≥ 0 then it is true? while if i try it on x = 0, 1/0 is undefined, and 0 ≥ 0 is true, therefore the biconditional statement is false?