selango wrote:sqrt(x^2)=|x|
yep. you should know this.
in fact, this fact is important and useful enough that you should
memorize it -- put it on a flash card, etc.
note that there are also some consequences -- for instance, the inequality x^2 < y^2 is equivalent to the inequality |x| < |y|.
similarly for inequalities involving hard numbers -- for instance,
x^2 < 16
is the same as |x| < 4
(which, in turn, is the same as -4 < x < 4)
also,
x^2 > 16
is the same as |x| > 4
(which, in turn, is the same as x > 4 or x < -4)
basically, the fact that √(x^2) = |x| allows you to take square roots of both sides in many situations involving squares, such as the above.
Ron has been teaching various standardized tests for 20 years.
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