Question

Proof that a^2>0=>a>0.

Answer 1

How can you prove something that isn't true?

Answer 2

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

Answer 3

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

Answer 4

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

Answer 5

anyway that's not true

Answer 6

Is this horse dead yet?

Answer 7

Thanks for all.

Answer 8

yw