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How would I solve this rational inequality:
(x/x-6)<2
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< 2. (1)
1. Assume that x - 6 > 0, i.e. x > 6.
Multiply both sides of (1) by (x-6), which is positive in this case. You will get an inequality
x < 2*(x-6) ---> x < 2x - 12 ---> 12 > x.
Thus the solution in this case is the set of real {x | 6 < x < 12}, i.e the interval (6,12).
2. Assume that x - 6 < 0, i.e. x < 6.
Multiply both sides of (1) by (x-6), which is negative in this case. You will get an inequality
x > 2*(x-6) ---> x > 2x - 12 ---> 12 > x. <---- Notice that I changed the inequality sign when multiplied by negative number!
Thus the solution in this case is the set of real {x | x < 6}, i.e the semi-infinite interval (
,6).
Answer. The solution is the union of two intervals: (
,6) U {6,12}.
The plot of the function f(x) =
is shown below.
Figure. Plot y =
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