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Mathematics 7 Online
OpenStudy (chris215):

-

OpenStudy (freckles):

It is important to know the definition of absolute value. |x|=x if x>0 or if x=0 |x|=-x if x<0 -- x>0 think we are looking to the right of 0 --x<0 think we are looking to the left of 0 So |x-8|=x-8 if x-8>0 or if x-8=0 |x-8|=-(x-8) if x-8<0

OpenStudy (freckles):

Your question says you are looking to the left of 8 which means you should be thinking of values less than 8

OpenStudy (freckles):

So which one will you use for |x-8|

OpenStudy (freckles):

the choices are A) x-8 B -(x-8)

OpenStudy (chris215):

a?

OpenStudy (freckles):

but |x-8|=x-8 if x>8 and |x-8|=-(x-8) if x<8

OpenStudy (anonymous):

you could yust mathway.com

OpenStudy (freckles):

you have x is approaches values to the left of 8 not to the right

OpenStudy (freckles):

since x is approaching to the left you have |x-8|=-(x-8)

OpenStudy (freckles):

if you had \[\lim_{x \rightarrow 8^+} \frac{|x-8|}{x-8}=\lim_{x \rightarrow 8^+}\frac{x-8}{x-8}=1\] but instead of that little + sign thingy you have the - sign thingy

OpenStudy (freckles):

\[\lim_{x \rightarrow 8^-}\frac{|x-8|}{x-8}=...\] and that - sign thing means you want to look to the left of 8 as you are approaching 8 which means you are looking at values then 8 which means you are looking at x<8 and in the definition I wrote |x-8|=-(x-8) if x<8 also if you don't see that x<8 if x-8<0 then try adding 8 on both sides to solve the inequality

OpenStudy (freckles):

@chris215 are you still confused what to do?

OpenStudy (freckles):

\[\lim_{x \rightarrow 8^-} \frac{|x-8|}{x-8}=\lim_{x \rightarrow 8^-} \frac{-(x-8)}{x-8}=...\]

OpenStudy (chris215):

-1?

OpenStudy (freckles):

yes

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