Solve the Quadratic Inequality: x²-6x+8 Greater Than Zero

Question

Solve the following equation:

x^2-6x+8>0

Video Solution

Step-by-Step Solution

Let's solve the inequality x26x+8>0 x^2 - 6x + 8 > 0 by breaking it down into steps:

**Step 1: Find the Roots of the Equation**
To solve the inequality, we first need to find the solutions to the equation x26x+8=0 x^2 - 6x + 8 = 0 . This can be done by factoring or using the quadratic formula.

Let's factor the quadratic expression:
x26x+8=(x2)(x4) x^2 - 6x + 8 = (x - 2)(x - 4)

The roots of the equation are x=2 x = 2 and x=4 x = 4 .

**Step 2: Test Intervals**
The roots divide the number line into three intervals: (,2) (-\infty, 2) , (2,4) (2, 4) , and (4,) (4, \infty) . We need to test each of these intervals to see where the inequality holds.

  • For x(,2) x \in (-\infty, 2) , choose x=0 x = 0 :
    (02)(04)=8 (0 - 2)(0 - 4) = 8 , which is positive, so x26x+8>0 x^2 - 6x + 8 > 0 .
  • For x(2,4) x \in (2, 4) , choose x=3 x = 3 :
    (32)(34)=1 (3 - 2)(3 - 4) = -1 , which is negative, so x26x+8<0 x^2 - 6x + 8 < 0 .
  • For x(4,) x \in (4, \infty) , choose x=5 x = 5 :
    (52)(54)=3 (5 - 2)(5 - 4) = 3 , which is positive, so x26x+8>0 x^2 - 6x + 8 > 0 .

**Conclusion**:
The inequality is satisfied for x<2 x < 2 and x>4 x > 4 .

Thus, the solution to the inequality x26x+8>0 x^2 - 6x + 8 > 0 is x<2 x < 2 or x>4 x > 4 .

The correct choice is x < 2,4 < x .

Answer

x < 2,4 < x


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