Is Sqrt(x^2) Always Equal to |x|?

  • Thread starter Thread starter TyErd
  • Start date Start date
  • Tags Tags
    Function Modulus
AI Thread Summary
The discussion centers on the mathematical expression sqrt(x^2) and its equivalence to |x|. While sqrt(x^2) yields a positive value, it represents the principal square root, which is always non-negative. The confusion arises from the fact that while x can be negative, the square root function only returns the positive root, thus aligning it with |x|. The example of plugging in -10 illustrates that sqrt(100) equals 10, reinforcing the point that sqrt(x^2) does not equal x for negative values. Ultimately, sqrt(x^2) is always equal to |x|, reflecting the nature of square roots and absolute values.
TyErd
Messages
297
Reaction score
0
Okay, when I enter into the calculator sqrt(x^2) it equals |x|. Since when? I thought sqrt(x^2) equals x and then when you go to sketch it, it will be a positive diagonal line through the origin whereas |x| is a reflection at the origin.
 
Physics news on Phys.org
A number squared is always positive. So if you plug in -10 you get sqrt(100) which is 10.
When you cancel out the square and the square root in a problem you do that because you're looking for the principle root aka the positive one.
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
Back
Top