Does Absolute Value Affect Fraction Equality?

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SUMMARY

The discussion confirms that the expression ##\frac{|x + 1|}{|x + 2|}## is indeed equal to ##\left|\frac{x + 1}{x + 2}\right|## for all values of x except x = -2. Participants demonstrated this equality by testing specific values of x, such as 10 and -10, and concluded that the absolute values can be applied separately to the numerator and denominator without affecting the overall equality. The underlying principle is based on the property of absolute values, specifically ##|xy| = |x||y|##.

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askor
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Is it correct that ##\frac{|x + 1|}{|x + 2|}## equal to ##\left|\frac{x + 1}{x + 2} \right|##?

Please explain, I don't understand.

Thank you
 
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Pick an x but not x=-2 and test it:

I pick x = 10

|x+1| / |x+2| = |11| / |12| = 11 / 12 = | 11/12 | = | (x+1) / (x+2) |

then pick x=-10

| x+1| / |x+2| = |-9| / |-8| = 9 / 8 = | 9/8 | = | -9/-8 | = | (x+1) / (x+2) |

Try other values for x and then decide if it is true or not.
 
askor said:
Is it correct that ##\frac{|x + 1|}{|x + 2|}## equal to ##\left|\frac{x + 1}{x + 2} \right|##?
Yes, the two expressions are identically equal.
askor said:
Please explain, I don't understand.
Think about the expressions x + 1 and x + 2. Each of them is negative, zero, or positive, depending on the value of x. Now, as long as ##x \ne -2##, ##\frac{x +1}{x + 2}## will have some value. Does it matter whether we take the absolute values of the numerator and denominator separately, or evaluate the fraction and then take its absolute value?
 
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askor said:
Is it correct that ##\frac{|x + 1|}{|x + 2|}## equal to ##\left|\frac{x + 1}{x + 2} \right|##?
Absolutely!

It's only ##|xy| = |x||y|## in disguise.
 
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