Question 72584
No it is not, well maybe if you were more precise and said
{{{sqrt(x^2)=abs(x)}}}is an identity, you would be right(The bars show absolute value)
The simple reason why (there are more complicated versions which have their purpose) is because when you take the square root of any number you get 2 answers. For instance
{{{sqrt(4)}}} equals plus or minus 2 (we need to have both). Since the absolute value of  both a positive and a negative number is positive, the absolute value can be used in this case. 
{{{abs(x)=a}}}
{{{x=0+-a}}}This is why {{{abs(x)}}} is used in the identity instead of x (ignore the 0).