Asked by ted

how do you solve this inequality
3x-2 < x+4/x-2
please help i don't get it

Answers

Answered by Reiny
You must mean:
3x-2 < (x+4)/(x-2) , so clearly x ≠ 2
(x-2)(3x-2) < x+4
3x^2 - 8x + 4 - x - 4 < 0
3x^2 - 9x < 0
3x(x-3) < 0

So the "critical values" are x=0 , x = 2, and x=3

test for a value of x<0
let x=-5 in original
-17 < -1/-7
-17 < 1/7 ? YES

test for a value between 0 and 2
let x=1
1 < 5/-1
1 < -5 ? NO

test for a value between 2 and 3
let x = 2.5
5.5 < 6.5/.5
5.5 < 13 ? , YES

test for a value x>3
let x=5
13 < 9/3
13 < 3 ? , NO

so we have x ≤ 0 OR 2 < x ≤ 3 , notice that x=2 in not included

To see that this is correct
go to my favourite graphing program
http://rechneronline.de/function-graphs/
and enter
3x-2 - (x+4)/(x-2)

in the window for "first graph"
change the "Range y-axis from" entries to -200 to 200

you will see the curve below the x-axis from -infinitity to 0
above the x-axis from 0 to the asymptote of 2
below the x-axis from 2 to 3, and
above the x-axis for x>3

Answered by ted
thanks so much :)
Answered by ted
what if all the values you put in do not work. how would you write the intervals.?
Answered by Damon
If the inequality can not be satisfied for any real value of x, then you just have to say that.
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