Question

$$\frac{ 6x }{ x-1 } \leq 1$$

Answer

-1/5<=x<1

Solution


Replace the inequality sign with an equal sign, so that we can solve it like a normal equation.
\[\frac{6x}{x-1}=1\]
Multiply both sides by \(x-1\).
\[6x=x-1\]
Subtract \(x\) from both sides.
\[6x-x=-1\]
Simplify  \(6x-x\)  to  \(5x\).
\[5x=-1\]
Divide both sides by \(5\).
\[x=-\frac{1}{5}\]
Also note that \(x\) is undefined at \(1\).
\[x\ne 1\]
From the values of \(x\) above, we have these 3 intervals to test.
\[\begin{aligned}&x\le -\frac{1}{5}\\&-\frac{1}{5}\le x\le 1\\&x\ge 1\end{aligned}\]
Pick a test point for each interval.
For the interval \(x\le -\frac{1}{5}\):
Let's pick \(x=-1\). Then, \(\frac{6\times -1}{-1-1}\le 1\).After simplifying, we get \(3\le 1\), which is
false
.
Drop this interval.
.
For the interval \(-\frac{1}{5}\le x\le 1\):
Let's pick \(x=0\). Then, \(\frac{6\times 0}{0-1}\le 1\).After simplifying, we get \(0\le 1\), which is
true
.
Keep this interval.
.
For the interval \(x\ge 1\):
Let's pick \(x=2\). Then, \(\frac{6\times 2}{2-1}\le 1\).After simplifying, we get \(12\le 1\), which is
false
.
Drop this interval.
.
Therefore,
\[-\frac{1}{5}\le x\le 1\]
Notice the equation contains \(x-1\) in the denominator. Since any denominator must not equal zero, the domain is restricted to \(x-1\ne 0\). Solving for \(x\), we have:
\[x\ne 1\]
Add the domain restrictions.
\[-\frac{1}{5}\le x<1\]