Question

Determine whether these are valid arguments. a) If x is a positive real number, then x2 is a positive real number. Therefore, if a2 is positive, where a is a real number, then a is a positive real number. b) If x2 ≠ 0, where x is a real number, then x ≠ 0. Let a be a real number with a2 ≠ 0; then a ≠ 0.

Answer 1

a) Not a valid argument:

If a² = 25, then a = ±5.

b) Valid argument:

If x = 0, then x² = 0.