Math Problem Statement

|x-1|^2 +2|x-1| <= 2

Solution

To solve the inequality x12+2x12|x-1|^2 + 2|x-1| \leq 2, let's use a substitution to simplify it. Let y=x1y = |x-1|. The inequality then becomes:

y2+2y2y^2 + 2y \leq 2

  1. Rearrange the inequality:

    y2+2y20y^2 + 2y - 2 \leq 0

  2. Solve the quadratic inequality y2+2y2=0y^2 + 2y - 2 = 0 to find the boundary points. We can use the quadratic formula:

    y=b±b24ac2ay = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} Here, a=1a = 1, b=2b = 2, and c=2c = -2:

    y=2±2241(2)21y = \frac{-2 \pm \sqrt{2^2 - 4 \cdot 1 \cdot (-2)}}{2 \cdot 1} y=2±4+82y = \frac{-2 \pm \sqrt{4 + 8}}{2} y=2±122y = \frac{-2 \pm \sqrt{12}}{2} y=2±232y = \frac{-2 \pm 2\sqrt{3}}{2} y=1±3y = -1 \pm \sqrt{3}

    Therefore, the roots are y=1+3y = -1 + \sqrt{3} and y=13y = -1 - \sqrt{3}. Since y=x10y = |x-1| \geq 0, we only consider the positive root:

    y=1+3y = -1 + \sqrt{3}

  3. Determine the intervals where the inequality holds:

    Since y=x1y = |x-1| is non-negative, the relevant root is y=1+3y = -1 + \sqrt{3}. We test the inequality y2+2y20y^2 + 2y - 2 \leq 0 within the interval [0,1+3][0, -1 + \sqrt{3}]:

    • When y=0y = 0: 02+2(0)2=20^2 + 2(0) - 2 = -2 (which satisfies the inequality).
    • When y=1+3y = -1 + \sqrt{3}: (1+3)2+2(1+3)2=0(-1 + \sqrt{3})^2 + 2(-1 + \sqrt{3}) - 2 = 0 (the boundary point).

    Thus, the inequality holds for 0y1+30 \leq y \leq -1 + \sqrt{3}.

  4. Translate back to xx using y=x1y = |x-1|:

    0x11+30 \leq |x-1| \leq -1 + \sqrt{3}

    This implies:

    1+3x1(1+3)-1 + \sqrt{3} \geq x - 1 \geq -(-1 + \sqrt{3})

    13x1311 - \sqrt{3} \leq x - 1 \leq \sqrt{3} - 1

    1+13x1+311 + 1 - \sqrt{3} \leq x \leq 1 + \sqrt{3} - 1

    23x32 - \sqrt{3} \leq x \leq \sqrt{3}

Therefore, the solution set for the inequality x12+2x12|x-1|^2 + 2|x-1| \leq 2 is:

x[23,3]x \in [2 - \sqrt{3}, \sqrt{3}]

Would you like more details or have any questions?

Related Questions:

  1. How would the solution change if the inequality were strict, x12+2x1<2|x-1|^2 + 2|x-1| < 2?
  2. What if the quadratic term had a different sign, such as x122x12|x-1|^2 - 2|x-1| \leq 2?
  3. How can we graphically represent the inequality and its solution set?
  4. How do absolute values affect the domain and range of functions?
  5. How would the inequality change if it involved a cubic term instead?

Tip:

When dealing with inequalities involving absolute values, substituting a variable for the absolute value term can simplify the problem significantly, allowing for easier algebraic manipulation.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Absolute Value
Quadratic Equations
Inequalities

Formulas

Quadratic Formula

Theorems

-

Suitable Grade Level

Advanced High School