Math Problem Statement

Solve the following inequality algebraically. 3, x, squared, plus, 10, x, plus, 5, is greater than or equal to, 2 3x 2 +10x+5≥2

Solution

We are asked to solve the inequality:

3x2+10x+523x^2 + 10x + 5 \geq 2

Step 1: Move all terms to one side

We start by subtracting 2 from both sides of the inequality:

3x2+10x+5203x^2 + 10x + 5 - 2 \geq 0

This simplifies to:

3x2+10x+303x^2 + 10x + 3 \geq 0

Step 2: Solve the corresponding equation

To understand the nature of the inequality, let's first solve the related quadratic equation:

3x2+10x+3=03x^2 + 10x + 3 = 0

We will use the quadratic formula:

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

where a=3a = 3, b=10b = 10, and c=3c = 3. Substituting these values into the quadratic formula:

x=10±1024(3)(3)2(3)x = \frac{-10 \pm \sqrt{10^2 - 4(3)(3)}}{2(3)}

x=10±100366x = \frac{-10 \pm \sqrt{100 - 36}}{6}

x=10±646x = \frac{-10 \pm \sqrt{64}}{6}

x=10±86x = \frac{-10 \pm 8}{6}

This gives two solutions:

x=10+86=26=13x = \frac{-10 + 8}{6} = \frac{-2}{6} = -\frac{1}{3}

and

x=1086=186=3x = \frac{-10 - 8}{6} = \frac{-18}{6} = -3

Thus, the solutions to the equation 3x2+10x+3=03x^2 + 10x + 3 = 0 are x=3x = -3 and x=13x = -\frac{1}{3}.

Step 3: Determine the intervals for the inequality

The solutions x=3x = -3 and x=13x = -\frac{1}{3} divide the real number line into three intervals:

  1. (,3)(-\infty, -3)
  2. (3,13)(-3, -\frac{1}{3})
  3. (13,)(-\frac{1}{3}, \infty)

We now test the inequality 3x2+10x+303x^2 + 10x + 3 \geq 0 in each of these intervals.

Step 4: Test the intervals

  • For x<3x < -3 (e.g., x=4x = -4): 3(4)2+10(4)+3=3(16)40+3=4840+3=11(positive)3(-4)^2 + 10(-4) + 3 = 3(16) - 40 + 3 = 48 - 40 + 3 = 11 \quad (\text{positive})

  • For 3<x<13-3 < x < -\frac{1}{3} (e.g., x=1x = -1): 3(1)2+10(1)+3=3(1)10+3=310+3=4(negative)3(-1)^2 + 10(-1) + 3 = 3(1) - 10 + 3 = 3 - 10 + 3 = -4 \quad (\text{negative})

  • For x>13x > -\frac{1}{3} (e.g., x=0x = 0): 3(0)2+10(0)+3=0+0+3=3(positive)3(0)^2 + 10(0) + 3 = 0 + 0 + 3 = 3 \quad (\text{positive})

Step 5: Conclusion

From the tests above, we see that the inequality 3x2+10x+303x^2 + 10x + 3 \geq 0 is satisfied when x3x \leq -3 or x13x \geq -\frac{1}{3}.

Thus, the solution to the inequality is:

x(,3][13,)x \in (-\infty, -3] \cup \left[-\frac{1}{3}, \infty\right)

Want more details or clarification?

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Related questions:

  1. How can we graph this quadratic inequality?
  2. What would be the solution if the inequality was 3x2+10x+3<03x^2 + 10x + 3 < 0?
  3. How do we solve inequalities with quadratic terms that don't factor easily?
  4. What does the discriminant tell us about the nature of the solutions for quadratic inequalities?
  5. How do we solve inequalities involving other types of polynomials (e.g., quartic)?

Tip:

To determine the sign of a quadratic function in different intervals, always check a point from each interval after finding the roots!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Inequalities
Quadratic Equations

Formulas

Quadratic formula: x = (-b ± √(b^2 - 4ac)) / 2a
Standard form of quadratic inequality: ax^2 + bx + c ≥ 0

Theorems

Quadratic formula
Interval testing for inequalities

Suitable Grade Level

Grades 9-11