To solve the inequality \(\frac{(x - 1)(x - 2)(x - 3)^2}{(x - 4)^2(x - 5)^3} < 0\), we need to determine where the expression is negative. This involves identifying the critical points and analyzing the sign of the expression in each interval.
Step 1: Identify Critical Points
The critical points occur where the numerator or denominator is zero:
- Numerator: \(x - 1 = 0 \Rightarrow x = 1\)
- Numerator: \(x - 2 = 0 \Rightarrow x = 2\)
- Numerator: \(x - 3 = 0 \Rightarrow x = 3\) (note: this is squared, so it does not change the sign)
- Denominator: \(x - 4 = 0 \Rightarrow x = 4\) (squared, so it does not change the sign)
- Denominator: \(x - 5 = 0 \Rightarrow x = 5\) (cubed, so it changes the sign)
Step 2: Sign Analysis
Now we analyze the sign of the expression in the intervals defined by these critical points:
- Interval: \((-∞, 1)\)
- Interval: \((1, 2)\)
- Interval: \((2, 3)\)
- Interval: \((3, 4)\)
- Interval: \((4, 5)\)
- Interval: \((5, ∞)\)
Testing Each Interval
Choose a test point from each interval to determine the sign of the expression:
- For \((-∞, 1)\), test \(x = 0\): \(\frac{(-)(-)(+)}{(+)(-)} < 0\) (negative)
- For \((1, 2)\), test \(x = 1.5\): \(\frac{(+)(-)(+)}{(+)(-)} > 0\) (positive)
- For \((2, 3)\), test \(x = 2.5\): \(\frac{(+)(+)(+)}{(+)(-)} < 0\) (negative)
- For \((3, 4)\), test \(x = 3.5\): \(\frac{(+)(+)(+)}{(+)(-)} < 0\) (negative)
- For \((4, 5)\), test \(x = 4.5\): \(\frac{(+)(+)(+)}{(-)(-)} > 0\) (positive)
- For \((5, ∞)\), test \(x = 6\): \(\frac{(+)(+)(+)}{(+)(+)} > 0\) (positive)
Step 3: Combine Results
The expression is negative in the intervals \((-∞, 1)\), \((2, 3)\), and \((3, 4)\). We also note that the expression is undefined at \(x = 4\) and \(x = 5\) and does not include these points.
Final Solution Set
The solution set for the inequality is:
- \((-∞, 1)\)
- \((2, 3)\)
- \((3, 4)\)
In interval notation, the solution set is: \((-∞, 1) \cup (2, 3) \cup (3, 4)\).