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16 (a) Rationalise the denominator of $$\frac{22}{\sqrt{11}}$$ Give your answer in its simplest form - Edexcel - GCSE Maths - Question 17 - 2019 - Paper 1

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16 (a) Rationalise the denominator of $$\frac{22}{\sqrt{11}}$$ Give your answer in its simplest form. (b) Show that $$\sqrt{3} \over 2\sqrt{3} - 1$$ can be written ... show full transcript

Worked Solution & Example Answer:16 (a) Rationalise the denominator of $$\frac{22}{\sqrt{11}}$$ Give your answer in its simplest form - Edexcel - GCSE Maths - Question 17 - 2019 - Paper 1

Step 1

Rationalise the denominator of $$\frac{22}{\sqrt{11}}$$

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Answer

To rationalise the denominator of 2211\frac{22}{\sqrt{11}}, we multiply both the numerator and the denominator by 11\sqrt{11}:

22111111=221111\frac{22}{\sqrt{11}} \cdot \frac{\sqrt{11}}{\sqrt{11}} = \frac{22\sqrt{11}}{11}

Since 22÷11=222 \div 11 = 2, the expression simplifies to:

2112\sqrt{11}

Step 2

Show that $$\sqrt{3} \over 2\sqrt{3} - 1$$ can be written in the form $$\frac{a + \sqrt{3}}{b}$$

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Answer

We start with the expression:

3231\frac{\sqrt{3}}{2\sqrt{3} - 1}

To simplify this, we multiply the numerator and the denominator by the conjugate of the denominator, which is 23+12\sqrt{3} + 1:

3(23+1)(231)(23+1)\frac{\sqrt{3}(2\sqrt{3} + 1)}{(2\sqrt{3} - 1)(2\sqrt{3} + 1)}

Calculating the denominator:

(23)212=121=11(2\sqrt{3})^2 - 1^2 = 12 - 1 = 11

Now, simplifying the numerator:

3(23)+3(1)=23+3=6+3\sqrt{3}(2\sqrt{3}) + \sqrt{3}(1) = 2 \cdot 3 + \sqrt{3} = 6 + \sqrt{3}

Thus, we have:

6+311\frac{6 + \sqrt{3}}{11}

In this form, we see that a=6a = 6 and b=11b = 11, both of which are integers.

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