Math Problem Statement

If (x-3-√2) then find(i) (x²-1/x²)

Solution

To find (x21x2)(x^2 - \frac{1}{x^2}) when x=3+2x = 3 + \sqrt{2}, let's go through the steps.

Step 1: Calculate x2x^2

Given x=3+2x = 3 + \sqrt{2}, we square both sides:

x2=(3+2)2=32+232+(2)2x^2 = (3 + \sqrt{2})^2 = 3^2 + 2 \cdot 3 \cdot \sqrt{2} + (\sqrt{2})^2

x2=9+62+2=11+62x^2 = 9 + 6\sqrt{2} + 2 = 11 + 6\sqrt{2}

Step 2: Calculate 1x2\frac{1}{x^2}

Now, let's find 1x2\frac{1}{x^2}. First, recall that the conjugate of x=3+2x = 3 + \sqrt{2} is 323 - \sqrt{2}, so:

1x=13+23232=32(3+2)(32)=3292=327\frac{1}{x} = \frac{1}{3 + \sqrt{2}} \cdot \frac{3 - \sqrt{2}}{3 - \sqrt{2}} = \frac{3 - \sqrt{2}}{(3 + \sqrt{2})(3 - \sqrt{2})} = \frac{3 - \sqrt{2}}{9 - 2} = \frac{3 - \sqrt{2}}{7}

Thus,

1x=327\frac{1}{x} = \frac{3 - \sqrt{2}}{7}

To square this:

1x2=(327)2=(32)272=962+249=116249\frac{1}{x^2} = \left(\frac{3 - \sqrt{2}}{7}\right)^2 = \frac{(3 - \sqrt{2})^2}{7^2} = \frac{9 - 6\sqrt{2} + 2}{49} = \frac{11 - 6\sqrt{2}}{49}

Step 3: Calculate x21x2x^2 - \frac{1}{x^2}

Now subtract 1x2\frac{1}{x^2} from x2x^2:

x21x2=(11+62)116249x^2 - \frac{1}{x^2} = (11 + 6\sqrt{2}) - \frac{11 - 6\sqrt{2}}{49}

We need to simplify this expression further. Let me handle the fraction carefully and compute the result.

The expression x21x2x^2 - \frac{1}{x^2} simplifies to:

x21x2=52849+300249x^2 - \frac{1}{x^2} = \frac{528}{49} + \frac{300\sqrt{2}}{49}

If you'd like, I can provide further details or verify any specific steps.

Would you like more details or have any questions? Here are five related questions you might find helpful:

  1. How do you calculate the conjugate of a binomial involving a square root?
  2. Can you explain the process of rationalizing a denominator?
  3. What is the significance of conjugates in simplifying expressions?
  4. How would you apply this method to a different binomial like 5+35 + \sqrt{3}?
  5. How can you check if your result is correct after performing algebraic operations?

Tip: When simplifying algebraic expressions, especially those involving square roots, using conjugates is a useful tool to eliminate radicals from denominators.

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Math Problem Analysis

Mathematical Concepts

Algebra
Conjugates
Square Roots
Rationalization

Formulas

x^2 = (3 + √2)^2
1/x^2 = (3 - √2)^2 / 7^2
x^2 - 1/x^2 = (11 + 6√2) - (11 - 6√2)/49

Theorems

Conjugate multiplication
Rationalization of binomial expressions

Suitable Grade Level

Grades 10-12