(2x-1)(x+3)(2-x)(1-x)2 X*(x+6)(x-9)(2x2+4x+9) 0

4 min read Jun 16, 2024
(2x-1)(x+3)(2-x)(1-x)2 X*(x+6)(x-9)(2x2+4x+9) 0

Solving the Polynomial Inequality: (2x-1)(x+3)(2-x)(1-x)2 * x*(x+6)(x-9)(2x2+4x+9) > 0

This problem involves solving a polynomial inequality where the expression on the left-hand side is a product of several factors. To find the solution, we'll use the following steps:

1. Finding the Critical Points

The critical points are the values of x where the expression on the left-hand side equals zero. These points divide the number line into intervals.

  • Factor 1: (2x-1) = 0 => x = 1/2
  • Factor 2: (x+3) = 0 => x = -3
  • Factor 3: (2-x) = 0 => x = 2
  • Factor 4: (1-x) = 0 => x = 1
  • Factor 5: x = 0
  • Factor 6: (x+6) = 0 => x = -6
  • Factor 7: (x-9) = 0 => x = 9
  • Factor 8: (2x2+4x+9) = 0 This quadratic has no real roots, as its discriminant is negative.

The critical points are: -6, -3, 0, 1/2, 1, 2, and 9.

2. Creating a Sign Chart

We'll create a sign chart to analyze the sign of the expression in each interval created by the critical points.

Interval (2x-1) (x+3) (2-x) (1-x)2 x (x+6) (x-9) (2x2+4x+9) Product
x < -6 - - + + - - - + +
-6 < x < -3 - - + + - + - + -
-3 < x < 0 - + + + - + - + +
0 < x < 1/2 - + + + + + - + -
1/2 < x < 1 + + + + + + - + +
1 < x < 2 + + + + + + - + +
2 < x < 9 + + - + + + - + -
x > 9 + + - + + + + + +

3. Analyzing the Sign Chart

The expression is greater than zero (positive) in the intervals where the product column has a plus sign.

Therefore, the solution to the inequality is:

x ∈ (-∞, -6) ∪ (-3, 0) ∪ (1/2, 1) ∪ (1, 2) ∪ (9, ∞)

Note: The quadratic factor (2x2+4x+9) is always positive because its discriminant is negative, meaning it has no real roots. Therefore, it does not affect the sign of the product.

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