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If x + (1)/(x) = sqrt(3), find the value of (x8 + 1)/(x4).

Mathematics

ScanSolve AI Answer

Answer

-1

Step-by-step solution

4 steps
  1. Square the given equation to find x2+1x2x^2 + \frac{1}{x^2}.

    Given the equation:

    x+1x=3x + \frac{1}{x} = \sqrt{3}

    Square both sides of the equation:

    (x+1x)2=(3)2\left(x + \frac{1}{x}\right)^2 = (\sqrt{3})^2

    Expand the left side using the formula (a+b)2=a2+2ab+b2(a+b)^2 = a^2 + 2ab + b^2:

    x2+2⋅x⋅1x+(1x)2=3x^2 + 2 \cdot x \cdot \frac{1}{x} + \left(\frac{1}{x}\right)^2 = 3 x2+2+1x2=3x^2 + 2 + \frac{1}{x^2} = 3

    Subtract 2 from both sides:

    x2+1x2=3−2x^2 + \frac{1}{x^2} = 3 - 2 x2+1x2=1x^2 + \frac{1}{x^2} = 1
  2. Square the result from Step 1 to find x4+1x4x^4 + \frac{1}{x^4}.

    We have x2+1x2=1x^2 + \frac{1}{x^2} = 1.
    Square both sides of this equation:

    (x2+1x2)2=(1)2\left(x^2 + \frac{1}{x^2}\right)^2 = (1)^2

    Expand the left side:

    (x2)2+2⋅x2⋅1x2+(1x2)2=1(x^2)^2 + 2 \cdot x^2 \cdot \frac{1}{x^2} + \left(\frac{1}{x^2}\right)^2 = 1 x4+2+1x4=1x^4 + 2 + \frac{1}{x^4} = 1

    Subtract 2 from both sides:

    x4+1x4=1−2x^4 + \frac{1}{x^4} = 1 - 2 x4+1x4=−1x^4 + \frac{1}{x^4} = -1
  3. Rewrite the expression to be evaluated.

    The expression to evaluate is x8+1x4\frac{x^8 + 1}{x^4}.
    We can split this fraction:

    x8+1x4=x8x4+1x4\frac{x^8 + 1}{x^4} = \frac{x^8}{x^4} + \frac{1}{x^4}

    Simplify the first term:

    x8+1x4=x8−4+1x4\frac{x^8 + 1}{x^4} = x^{8-4} + \frac{1}{x^4} x8+1x4=x4+1x4\frac{x^8 + 1}{x^4} = x^4 + \frac{1}{x^4}
  4. Substitute the value found in Step 2.

    From Step 2, we found that x4+1x4=−1x^4 + \frac{1}{x^4} = -1.
    Therefore,

    x8+1x4=−1\frac{x^8 + 1}{x^4} = -1

    The final answer is −1-1.

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