I'm really confused!

[SilverSprite]

Now i was taught that when you have an equation such as x^2=9 and you take the sqrt bs of this equation sqrt(x^2)=sqrt(p) you get |x|=3. I was also told that sqrt only returns a positive(non-negative) value. I asked a friend but he was too busy to finish explaining and i just got even more confused. So my question is why do you need the abs value on the x if you know that sqrt is non-negative?

[bugzpodder]

because x can be negative also. whos that friend? he must have told you about this or hes very irresponsible! did he also tell you that x=3 and x=-3 both are solutions to x^2=9 so when we are solving for x (finding the roots) we are looking for both values of x thus we need the absolute value (b/c if not, we have x=sqrt(9)=3, which is only one root)!

[SilverSprite]

thats not what i dont understand! i dont understand how the absolute value gives you both these values?

[bugzpodder]

ok

|-3|=3

and |3|=3

do u agree with that?

if you do, then you would agree
|x|=3 yields x=3 or -3

[SilverSprite]

Oh i see (i think) now i get it now. Thanx a bunch!