Solve Quadratic Inequality: 2x²-12x+18 Greater Than Zero

Question

Solve the following equation:

2x^2-12x+18>0

Video Solution

Step-by-Step Solution

To solve this problem, let's first find the solution to the related equation:

  • Solve the equation 2x212x+18=02x^2 - 12x + 18 = 0.

The quadratic equation is:

2x212x+18=02x^2 - 12x + 18 = 0.

Dividing the entire equation by 2 simplifies it to:

x26x+9=0x^2 - 6x + 9 = 0.

This factors easily as a perfect square:

(x3)2=0(x - 3)^2 = 0.

This gives a double root at

x=3x = 3.

  • Analyzing intervals:

The roots of the equation tell us that the parabola touches the x-axis at x=3x = 3, and this point is where the inequality would potentially change sign. Since it's a perfect square, the expression x26x+9=0x^2 - 6x + 9 = 0 means the quadratic doesn't cross the x-axis and is zero at x=3x = 3. Therefore, for the inequality 2x212x+18>02x^2 - 12x + 18 > 0, we test the intervals:

Test for x<3x < 3 and x>3x > 3:

  • As the parabola opens upwards (coefficient of x2x^2 is positive), the inequality 2x212x+18>02x^2 - 12x + 18 > 0 holds for all real xx except x=3x = 3.

Thus, the inequality is true for all xx except when x=3x = 3.

The correct solution is:

x3x ≠ 3

Answer

x3 x ≠ 3


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