[Math] Limit Absolute Value

limits

I do not understand how absolute value effects this, and why is what I have done wrong. Is the way I tackled the problem correct or am I totally wrong?

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I have looked at this post limits, but the definition of absolute value I dont get, I thought |-2|=2, the same would |-x|=x. What am I not getting?

Best Answer

Suppose you didn't know whether $x$ is positive or negative, then how will you analyse the expression $\Large \frac{2x-5}{|3x+2|}$?

You will have to consider two cases:

(1)If $x$ is positive, then $\Large \frac{2x-5}{|3x+2|}=\Large \frac{2x-5}{3x+2}$

(2)If $x$ is negative, then $\Large \frac{2x-5}{|3x+2|}=\Large \frac{2x-5}{-(3x)+2}$

But in your example, we are given that $x\rightarrow-\infty$

Since $x\rightarrow-\infty$, what you are doing is, dividing numerator by negative value, which is $x$ and denominator by positive value, which is $|x|$.

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