Math Problem Statement

Solve the following inequality.

5 left parenthesis x squared minus 1 right parenthesis greater than 24 x

Solution

The inequality is given as:

5(x21)>24x5(x^2 - 1) > 24x

Step 1: Expand the left side of the inequality

Distribute the 55 across the terms inside the parentheses:

5x25>24x5x^2 - 5 > 24x

Step 2: Rearrange the inequality

Move all terms to one side so that the right side is 00:

5x224x5>05x^2 - 24x - 5 > 0

Step 3: Solve the corresponding quadratic equation

To solve the inequality, first solve the quadratic equation:

5x224x5=05x^2 - 24x - 5 = 0

Use the quadratic formula:

x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

where a=5a = 5, b=24b = -24, and c=5c = -5. Substituting these values into the formula:

x=(24)±(24)24(5)(5)2(5)x = \frac{-(-24) \pm \sqrt{(-24)^2 - 4(5)(-5)}}{2(5)} x=24±576+10010x = \frac{24 \pm \sqrt{576 + 100}}{10} x=24±67610x = \frac{24 \pm \sqrt{676}}{10} x=24±2610x = \frac{24 \pm 26}{10}

Thus, the two solutions are:

x1=24+2610=5010=5x_1 = \frac{24 + 26}{10} = \frac{50}{10} = 5 x2=242610=210=0.2x_2 = \frac{24 - 26}{10} = \frac{-2}{10} = -0.2

Step 4: Analyze the inequality

The quadratic inequality 5x224x5>05x^2 - 24x - 5 > 0 has solutions when the quadratic expression is positive. The roots x=5x = 5 and x=0.2x = -0.2 divide the number line into three intervals:

  1. x<0.2x < -0.2
  2. 0.2<x<5-0.2 < x < 5
  3. x>5x > 5

To determine where the inequality holds, test points from each interval in the expression 5x224x5>05x^2 - 24x - 5 > 0:

  • For x=1x = -1 (in the interval x<0.2x < -0.2):

5(1)224(1)5=5(1)+245=24>05(-1)^2 - 24(-1) - 5 = 5(1) + 24 - 5 = 24 > 0 The inequality holds for x<0.2x < -0.2.

  • For x=0x = 0 (in the interval 0.2<x<5-0.2 < x < 5):

5(0)224(0)5=5<05(0)^2 - 24(0) - 5 = -5 < 0 The inequality does not hold for 0.2<x<5-0.2 < x < 5.

  • For x=6x = 6 (in the interval x>5x > 5):

5(6)224(6)5=1801445=31>05(6)^2 - 24(6) - 5 = 180 - 144 - 5 = 31 > 0 The inequality holds for x>5x > 5.

Step 5: Final solution

The inequality 5x224x5>05x^2 - 24x - 5 > 0 holds for:

x<0.2orx>5x < -0.2 \quad \text{or} \quad x > 5

Thus, the solution to the inequality is:

x(,0.2)(5,)x \in (-\infty, -0.2) \cup (5, \infty)

Let me know if you would like further details or explanations!

Related Questions:

  1. How do we graph quadratic inequalities?
  2. What is the quadratic formula and how does it work?
  3. How do we factor quadratics if possible?
  4. Can we solve inequalities graphically?
  5. What is the significance of the discriminant in the quadratic formula?

Tip:

Always test points in different intervals to determine where a quadratic inequality holds true after solving the related equation.

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Math Problem Analysis

Mathematical Concepts

Inequalities
Quadratic Equations
Algebra

Formulas

Quadratic equation formula: ax^2 + bx + c = 0
Quadratic formula: x = (-b ± √(b^2 - 4ac)) / 2a

Theorems

Quadratic Formula
Properties of Inequalities

Suitable Grade Level

Grades 9-12