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The sum of the squares of the roots of $|x-2|^2+|x-2|-2=0$ and the squares of the roots of $x^2-2|x-3|-5=0$, is

The correct answer is
36

Sum of Squares of Roots for Absolute Value Equations

The problem requires finding the sum of the squares of the roots for two distinct equations involving absolute values.

Solving Equation 1: $|x-2|^2+|x-2|-2=0$

  1. Let $y = |x-2|$. The equation transforms into a quadratic equation in terms of $y$:

    $y^2 + y - 2 = 0$

  2. Factor the quadratic equation:

    $(y+2)(y-1) = 0$

    This gives potential values for $y$: $y=-2$ or $y=1$.

  3. Since $y = |x-2|$, $y$ must be non-negative ($y \ge 0$). Therefore, we discard $y=-2$.

    We have $|x-2| = 1$.

  4. Solve for $x$:

    This implies either $x-2 = 1$ or $x-2 = -1$.

    • $x-2 = 1 \implies x = 3$
    • $x-2 = -1 \implies x = 1$
  5. The roots of the first equation are $1$ and $3$.
  6. Calculate the sum of the squares of these roots:

    Sum of squares = $1^2 + 3^2 = 1 + 9 = 10$.

Solving Equation 2: $x^2-2|x-3|-5=0$

We need to consider two cases based on the sign of $(x-3)$.

Case 1: $x \ge 3$

  1. In this case, $|x-3| = x-3$. Substitute this into the equation:

    $x^2 - 2(x-3) - 5 = 0$

  2. Simplify and solve the resulting quadratic equation:

    $x^2 - 2x + 6 - 5 = 0$

    $x^2 - 2x + 1 = 0$

    $(x-1)^2 = 0$

    This yields $x=1$.

  3. Check the condition: The solution $x=1$ does not satisfy the condition $x \ge 3$. Therefore, there are no roots from this case.

Case 2: $x < 3$

  1. In this case, $|x-3| = -(x-3) = 3-x$. Substitute this into the equation:

    $x^2 - 2(3-x) - 5 = 0$

  2. Simplify and solve the resulting quadratic equation:

    $x^2 - 6 + 2x - 5 = 0$

    $x^2 + 2x - 11 = 0$

  3. Find the roots using the quadratic formula $x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}$:

    $x = \frac{-2 \pm \sqrt{2^2 - 4(1)(-11)}}{2(1)}$

    $x = \frac{-2 \pm \sqrt{4 + 44}}{2}$

    $x = \frac{-2 \pm \sqrt{48}}{2}$

    $x = \frac{-2 \pm 4\sqrt{3}}{2}$

    $x = -1 \pm 2\sqrt{3}$

  4. Check the condition:
    • $x = -1 + 2\sqrt{3} \approx -1 + 2(1.732) = 2.464$. This satisfies $x < 3$.
    • $x = -1 - 2\sqrt{3} \approx -1 - 3.464 = -4.464$. This also satisfies $x < 3$.
  5. The roots of the second equation are $-1 + 2\sqrt{3}$ and $-1 - 2\sqrt{3}$.
  6. Calculate the sum of the squares of these roots. For the equation $x^2 + 2x - 11 = 0$, let the roots be $x_3$ and $x_4$. Using Vieta's formulas:
    • Sum of roots: $x_3 + x_4 = -\frac{2}{1} = -2$.
    • Product of roots: $x_3 x_4 = \frac{-11}{1} = -11$.
    The sum of squares is given by $(x_3 + x_4)^2 - 2x_3 x_4$:

    Sum of squares = $(-2)^2 - 2(-11) = 4 + 22 = 26$.

Calculating the Total Sum of Squares

Add the sum of the squares of the roots from both equations:

Total Sum = (Sum of squares from Eq 1) + (Sum of squares from Eq 2)

Total Sum = $10 + 26 = 36$.

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