Question 2, AQA AS Maths Pure Core 1, May 2011

In summary, \(\sqrt{48}\) can be expressed as \(4\sqrt{3}\) and \(\displaystyle \frac{\sqrt{48}+2\sqrt{27}}{\sqrt{12}}\) simplifies to 5. Also, \(\displaystyle \frac{1-5\sqrt{5}}{3+\sqrt{5}}\) can be rewritten as \(7-4\sqrt{5}\).
  • #1
CaptainBlack
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(a) (i) Express \(\sqrt{48}\) in the form \(k\sqrt{3}\), where \(k\) is an integer. (1 mark)

...(ii) Simplify \(\displaystyle \frac{\sqrt{48}+2\sqrt{27}}{\sqrt{12}}\) giving your answer as an integer. (3 marks)

(b) Express \(\displaystyle \frac{1-5\sqrt{5}}{3+\sqrt{5}}\) in the form \(m+n\sqrt{5}\), where m and n are integers. (4 marks)

CB
 
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  • #2
Answer

(a) (i)
Since \(48=16 \times 3\) we have: \(\sqrt{48}=\sqrt{16 \times 3}=4\sqrt{3}\).

(a) (ii) \[\frac{\sqrt{48}+2\sqrt{27}}{\sqrt{12}}=\frac{4 \sqrt{3}+2 \times 3 \sqrt{3}}{2 \sqrt{3}}=\frac{4+6}{2}=5\]

(b) We multiply top and bottom by \( 3-\sqrt{5} \):

\[\frac{1-5\sqrt{5}}{3+\sqrt{5}}=\frac{(1-5\sqrt{5})(3-\sqrt{5})}{(3+\sqrt{5})(3-\sqrt{5})}=\frac{3-15 \sqrt{5}- \sqrt{5}+5( \sqrt{5})^2}{9-5}=\frac{28-16\sqrt{5}}{4}=7-4\sqrt{5}\]

CB
 

FAQ: Question 2, AQA AS Maths Pure Core 1, May 2011

What is Question 2 asking for?

Question 2 on the AQA AS Maths Pure Core 1 exam in May 2011 is asking for the value of x when given a quadratic equation in the form of ax^2 + bx + c = 0.

How do I solve a quadratic equation?

To solve a quadratic equation, you can use the quadratic formula: x = (-b ± √(b^2-4ac)) / 2a, where a, b, and c are the coefficients of the equation. You can also factor the equation or use completing the square method.

Can I use a calculator on this question?

No, calculators are not allowed on the AQA AS Maths Pure Core 1 exam. You will need to use algebraic methods to solve the equation.

Are there any specific steps I need to follow to solve this question?

Yes, when solving a quadratic equation, you should always start by rearranging the equation into the standard form of ax^2 + bx + c = 0. Then, identify the values for a, b, and c and substitute them into the quadratic formula or use other methods of solving.

Can I check my answer to this question?

Yes, you can always check your answer by substituting the value of x back into the original equation and seeing if it satisfies the equation. You can also graph the equation and see if the x-intercepts match your answer.

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