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Nov 26 2013 02:23pm
(x+6)/(x-6)<=1

obviously the answer is x<6, but how would i solve this
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Nov 26 2013 02:55pm
shit man, engineering student here and I have no idea. Working on it though haha
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Nov 26 2013 03:01pm
You can multiply both sides by the denominator squared... in this case (x-6)^2

You then have (x+6)(x-6) ≤ (x-6)^2
x^2 -36 ≤ x^2 - 12x + 36
12x ≤ 72
x ≤ 6

Given that the graph is asymptotic at x = 6 and thus doesn't exist, I guess you drop the 'equal to' portion. I don't really know the proper way to describe that, it's been too long!
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Nov 26 2013 03:03pm
Quote (chr0me357 @ 26 Nov 2013 15:01)
You can multiply both sides by the denominator squared... in this case (x-6)^2

You then have (x+6)(x-6) ≤ (x-6)^2
x^2 -36 ≤ x^2 - 12x + 36
12x ≤ 72
x ≤ 6

Given that the graph is asymptotic at x = 6 and thus doesn't exist, I guess you drop the 'equal to' portion. I don't really know the proper way to describe that, it's been too long!


Yeah it took me awhile to realize you have to multiply by the denominator squared... whats the reason for this?
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Nov 26 2013 03:05pm
holy shit thanks, i knew there was a simple answer i was missing
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Nov 26 2013 03:09pm
When you evaluate a limit, you can rationalize the denominator by multiplying by its conjugate
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Nov 26 2013 04:44pm
Quote (XxAviated @ 26 Nov 2013 20:23)
(x+6)/(x-6)<=1
obviously the answer is x<6, but how would i solve this


'chr0me357' gave you the answer
but another way is to look at the graph, just visualise it:

starting just below y=1 at the left (minus infinity), then constantly decreasing slowly
crossing y=0 at x=-6, y=-1 at x=0 and then decreasing asymptotically until just before x=6 where is becomes singular
at x=6 it jump from minus infinity to plus infinity and starts decreasing towards y=1
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