More Complex Rational Inequalities
When working with more complex rational inequalities, the process remains the same, but you'll need to handle multiple factors carefully. Break down expressions like x(x+12)<7 by getting everything to one side: xx+12−7x<0, which simplifies to x(x−4)(x−3)<0.
The sign of a rational expression changes whenever you cross a critical value. Remember that when a factor in the numerator equals zero, the entire expression equals zero. When a factor in the denominator equals zero, the expression is undefined, and you must exclude that value from your solution.
For products of rational expressions like x(x2+1)(x−2)≥0, identify all zeros and use the same testing strategy. The expression changes sign only at points where factors equal zero (assuming an odd power). For this example, checking test points in each region reveals that (−∞,−1)∪[0,1)∪[2,∞) is the solution.
Remember: When an inequality includes "≥" or "≤", include the points where the numerator equals zero in your solution. For strict inequalities (> or <), exclude those points.
When comparing two fractions like x−35≥x+13, combine them into a single fraction by finding a common denominator. This transforms the problem into our standard form (x−3)(x+1)2(x+7)≥0, which you can then solve using critical values and test points.