## viniterranova Proof that a^2>0=>a>0. 2 years ago 2 years ago

1. Mertsj

How can you prove something that isn't true?

2. ChrisS

right... any number squared is greater than 0. example let a=-2 -2^2=4 so a<0 and a^2>0

3. Callisto

for any real number a^2>0 but $\sqrt{a ^{2}}$ can be a or -a

4. Callisto

for complex number $i ^{2}=-1$ where $i=\sqrt{-1}$

5. Callisto

anyway that's not true

6. Mertsj