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Question

If x + 1/x = 2, then find the value of x99 + 1/x99.

The correct answer is

2

To find the value of $x^{99} + \frac{1}{x^{99}}$ given the equation $x + \frac{1}{x} = 2$, we first need to determine the value of $x$. Let's follow these steps:

Solving the Initial Equation for x

We are given the equation:

$$x + \frac{1}{x} = 2$$

To solve for $x$, we can eliminate the fraction by multiplying the entire equation by $x$ (assuming $x \neq 0$):

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

Now, rearrange the terms to form a standard quadratic equation:

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

This is a perfect square trinomial, which can be factored as:

$$(x-1)^2 = 0$$

Taking the square root of both sides gives:

$$x - 1 = 0$$

Therefore, the value of $x$ is:

$$x = 1$$

Calculating x99 + 1/x99

Now that we have found $x = 1$, we can substitute this value into the expression we need to evaluate:

$$x^{99} + \frac{1}{x^{99}}$$

Substitute $x = 1$ into the expression:

$$1^{99} + \frac{1}{1^{99}}$$

Calculate the powers:

  • $1^{99} = 1$
  • $\frac{1}{1^{99}} = \frac{1}{1} = 1$

Now, add the results:

$$1 + 1 = 2$$

So, the value of $x^{99} + \frac{1}{x^{99}}$ is 2.

Final Answer Verification

The steps clearly show that when $x + \frac{1}{x} = 2$, the value of $x$ must be 1. Substituting $x=1$ into $x^{99} + \frac{1}{x^{99}}$ yields $1^{99} + \frac{1}{1^{99}} = 1 + 1 = 2$. This confirms our result.

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Important Questions from Algebra

  1. In the given question, two equations numbered l and II are given. Solve both the equations and mark the appropriate answer.

    I. x2 – 26x + 165 = 0

    II. y2 – 38y + 357 = 0

  2. Factorize the following:

    (x 2- 6xy + 9y 2) - 25

  3. If P and Q are the points on the line Joining A(-2, 5) and B(3, 1) such that

    AP = PQ = QB, then the mid point of PQ is 

  4. If a number and its reciprocal added it becomes 6, then what will be sum of its square and square of its reciprocal?

  5. If 3x + 2y = 15, and xy = 6. Find the value of (3x3/2) + (4y3/9).

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