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Simplify $$\frac{7 + \sqrt{5}}{\sqrt{5} - 1}$$ giving your answer in the form $a + \frac{b}{\sqrt{5}}$, where $a$ and $b$ are integers. - Edexcel - A-Level Maths Pure - Question 3 - 2013 - Paper 1

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Simplify--$$\frac{7-+-\sqrt{5}}{\sqrt{5}---1}$$--giving-your-answer-in-the-form-$a-+-\frac{b}{\sqrt{5}}$,-where-$a$-and-$b$-are-integers.-Edexcel-A-Level Maths Pure-Question 3-2013-Paper 1.png

Simplify $$\frac{7 + \sqrt{5}}{\sqrt{5} - 1}$$ giving your answer in the form $a + \frac{b}{\sqrt{5}}$, where $a$ and $b$ are integers.

Worked Solution & Example Answer:Simplify $$\frac{7 + \sqrt{5}}{\sqrt{5} - 1}$$ giving your answer in the form $a + \frac{b}{\sqrt{5}}$, where $a$ and $b$ are integers. - Edexcel - A-Level Maths Pure - Question 3 - 2013 - Paper 1

Step 1

Step 1: Multiply the Numerator and Denominator

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Answer

To simplify the expression, we will multiply both the numerator and the denominator by the conjugate of the denominator, which is 5+1\sqrt{5} + 1.

(7+5)(5+1)(51)(5+1)\frac{(7 + \sqrt{5})(\sqrt{5} + 1)}{(\sqrt{5} - 1)(\sqrt{5} + 1)}

Step 2

Step 2: Simplify the Denominator

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Answer

Calculating the denominator:

(5)2(1)2=51=4(\sqrt{5})^2 - (1)^2 = 5 - 1 = 4

Step 3

Step 3: Expand the Numerator

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Answer

Now, expanding the numerator:

(7+5)(5+1)=75+7+5+5=7+5+85=12+85(7 + \sqrt{5})(\sqrt{5} + 1) = 7\sqrt{5} + 7 + 5 + \sqrt{5} = 7 + 5 + 8\sqrt{5} = 12 + 8\sqrt{5}

Step 4

Step 4: Combine the Results

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Answer

Putting it all together, we have:

12+854\frac{12 + 8\sqrt{5}}{4}

This simplifies to:

3+253 + 2\sqrt{5}

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