## UnkleRhaukus Group Title Negation one year ago one year ago

1. UnkleRhaukus Group Title

(a) $\neg(\pi>3.2)\quad\longrightarrow\quad\pi\leq 3.2$(b) $\neg (x < 0)\quad\longrightarrow\quad x\geq 0$(c) $\neg(x^2 > 0)\quad\longrightarrow\quad x=0$ (d) $\neg(x = 1)\quad\longrightarrow\quad x\neq 1$(e) $\neg\neg \psi\quad\longrightarrow\quad \psi$

2. UnkleRhaukus Group Title

any mistakes?

3. hartnn Group Title

(c) ?

4. UnkleRhaukus Group Title

sure?

5. hartnn Group Title

its correct. except for imaginary x

6. UnkleRhaukus Group Title

so this is a more gerneral answer to c)$\neg(x^2 > 0)\quad\longrightarrow\quad x\in\Im$?

7. hartnn Group Title

yup. but if it is mentioned that x is real, then x=0. else x belongs to imaginary.

8. hartnn Group Title

sorry, x belongs to imaginary or x=0

9. UnkleRhaukus Group Title

$\longrightarrow \Re(x)=0$

10. UnkleRhaukus Group Title

im a bit confused, what if x is complex

11. hartnn Group Title

but, if x is complex then u x^2 can be positive. yes,even i was thinking that. better assume x as real then x=0

12. UnkleRhaukus Group Title

im not sure

13. UnkleRhaukus Group Title

maybe all i can do is this $\neg(x^2 > 0)\quad\longrightarrow\quad x^2\leq0$

14. UnkleRhaukus Group Title

@AccessDenied

15. UnkleRhaukus Group Title

what is the best answer for part (c)

16. Jemurray3 Group Title

Typically when you're talking about statements of logic you work in real numbers for simplicity just to get the ideas of negation and implication and all that stuff down. I would mark (c) as correct. Furthermore, since complex numbers are not ordered, the symbols don't make sense for complex numbers, lending credence to the assumption that the quantities in question are real.

17. UnkleRhaukus Group Title

so i should leave it as i had it at the top of the page then ,

18. Jemurray3 Group Title

I would say yes.

19. UnkleRhaukus Group Title

thanks