Question

Difficulty: EasySurds and Rationalization of Denominators

What is the simplified form of 63+3\frac{6}{3 + \sqrt{3}} after rationalizing the denominator?

  1. 3−33 - \sqrt{3}Answer
  2. B
    3+33 + \sqrt{3}
  3. C
    3\sqrt{3}
  4. D
    3−233 - 2\sqrt{3}

Answer

3−33 - \sqrt{3}
Multiplying the numerator and denominator by the conjugate 3−33 - \sqrt{3} converts the denominator into 32−(3)2=63^2 - (\sqrt{3})^2 = 6. Dividing 6(3−3)6(3 - \sqrt{3}) by 66 yields 3−33 - \sqrt{3}.

Step-by-Step Solution

1
Identify the conjugate of the denominator
The conjugate of 3+33 + \sqrt{3} is 3−33 - \sqrt{3}.
To eliminate the surd from the denominator, multiply by its conjugate.
2
Multiply the numerator and denominator by the conjugate
6(3−3)(3+3)(3−3)\frac{6(3 - \sqrt{3})}{(3 + \sqrt{3})(3 - \sqrt{3})}
Multiplying by 3−33−3\frac{3 - \sqrt{3}}{3 - \sqrt{3}} is equivalent to multiplying by 1.
3
Simplify the denominator using difference of two squares
(3)2−(3)2=9−3=6(3)^2 - (\sqrt{3})^2 = 9 - 3 = 6
The product (a+b)(a−b)=a2−b2(a+b)(a-b) = a^2 - b^2 simplifies the denominator to a rational number.
4
Divide the numerator by the denominator
6(3−3)6=3−3\frac{6(3 - \sqrt{3})}{6} = 3 - \sqrt{3}
Canceling out the common factor of 6 gives the final simplified surd expression.

Key Concept

Rationalization of Binomial Denominators
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