Math Problem Statement

Solve the inequality: x^3 + 2x^2 + x + 2 > 0

Solution

The inequality provided in the image is:

x3+2x2+x+2>0x^3 + 2x^2 + x + 2 > 0

Let's solve this inequality step by step.

1. Factor the cubic expression if possible:

We attempt factoring x3+2x2+x+2x^3 + 2x^2 + x + 2 using methods such as synthetic division or trial values for potential roots.

Step 1: Trial and Error with Rational Roots

Let's test small integer values for xx. Substituting x=1x = -1:

(1)3+2(1)2+(1)+2=1+21+2=20(-1)^3 + 2(-1)^2 + (-1) + 2 = -1 + 2 - 1 + 2 = 2 \neq 0

x=1x = -1 is not a root. Now, test x=2x = -2:

(2)3+2(2)2+(2)+2=8+82+2=0(-2)^3 + 2(-2)^2 + (-2) + 2 = -8 + 8 - 2 + 2 = 0

x=2x = -2 is a root of the cubic equation.

Step 2: Synthetic Division

Now that we know x=2x = -2 is a root, we divide x3+2x2+x+2x^3 + 2x^2 + x + 2 by x+2x + 2:

x3+2x2+x+2÷(x+2)x^3 + 2x^2 + x + 2 \div (x + 2)

The quotient is x2+0x+1x^2 + 0x + 1. Therefore, the factorization is:

x3+2x2+x+2=(x+2)(x2+1)x^3 + 2x^2 + x + 2 = (x + 2)(x^2 + 1)

2. Solve the Inequality

Now we have:

(x+2)(x2+1)>0(x + 2)(x^2 + 1) > 0

Analyze Each Factor:

  • x+2>0x + 2 > 0 when x>2x > -2.
  • x2+1>0x^2 + 1 > 0 for all real xx since x2+1x^2 + 1 is always positive.

Thus, the inequality holds when x+2>0x + 2 > 0, i.e., x>2x > -2.

3. Final Answer:

The solution to the inequality x3+2x2+x+2>0x^3 + 2x^2 + x + 2 > 0 is:

x>2x > -2

Would you like a detailed explanation of the synthetic division or have any questions?

Here are 5 related questions for practice:

  1. What are the steps to factor a cubic polynomial?
  2. How do you perform synthetic division with polynomials?
  3. What is the significance of x2+1>0x^2 + 1 > 0 in this problem?
  4. How would the solution change if the inequality was \leq?
  5. Can a cubic polynomial have more than one real root?

Tip: When solving polynomial inequalities, always check if the expression can be factored, and use synthetic division to simplify the process.

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomial Inequalities
Synthetic Division

Formulas

Cubic Polynomial Factorization
Synthetic Division

Theorems

Rational Root Theorem
Inequality Analysis

Suitable Grade Level

Grades 10-12