Surds worksheet
10 GCSE practice questions with answers, free to print. Every sheet is generated, so you can make a fresh one whenever you need it.
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4 marks
(a)
Write \(\sqrt{ 54 }\) in the form \(a\sqrt{b}\), where \(a\) and \(b\) are integers and \(b\) is as small as possible.
(b)Simplify \(4\sqrt{ 32 }\)
Give your answer in the form \(a\sqrt{b}\), where \(b\) is as small as possible.
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2 marks
\(\sqrt{n} = 7\sqrt{ 5 }\)
Calculate the value of \(n\).
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6 marks
(a)
Write \(\sqrt{ 27 } + \sqrt{ 12 }\) in the form \(a\sqrt{b}\), where \(b\) is as small as possible.
(b)Write \(\sqrt{ 396 } - \sqrt{ 99 }\) in the form \(a\sqrt{b}\), where \(b\) is as small as possible.
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7 marks
(a)
Multiply out the brackets and simplify \(\sqrt{ 13 }\left(\sqrt{ 13 } + 5\right)\)
(b)Multiply out the brackets and simplify \(\left(3 + \sqrt{ 7 }\right)\left(2 - \sqrt{ 7 }\right)\)
(c)Multiply out the brackets and simplify \(\left(6 + \sqrt{ 6 }\right)\left(6 - \sqrt{ 6 }\right)\)
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4 marks
(a)
Rationalise the denominator of \(\frac{ 20 }{\sqrt{ 5 } }\)
Give your answer in its simplest form.
(b)Rationalise the denominator of \(\frac{ 9 }{\sqrt{ 5 } }\)
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6 marks
(a)
Rationalise the denominator and simplify \(\frac{ 39 }{ 4 + \sqrt{ 3 } }\)
Give your answer in the form \(p - q\sqrt{ 3 }\), where \(p\) and \(q\) are integers.
(b)Rationalise the denominator and simplify \(\frac{ 34 }{ 6 - \sqrt{ 2 } }\)
Give your answer in the form \(p + q\sqrt{ 2 }\), where \(p\) and \(q\) are integers.
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5 marks
(a)
Write \(\sqrt{ 20 } + \sqrt{ 5 }\) as a single surd \(\sqrt{c}\), where \(c\) is an integer.
(b)Explain why \(\sqrt{ 3 } + \sqrt{ 5 }\) cannot be written as a single surd in the same way.
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6 marks
A rectangle has width \(\sqrt{ 90 }\) cm and length \(\sqrt{ 160 }\) cm.
(a)Calculate the area of the rectangle.
(b)Calculate the perimeter of the rectangle.
Give your answer in the form \(a\sqrt{b}\) cm, where \(b\) is as small as possible.
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4 marks
(a)
Simplify \(\sqrt{ 147 }\) fully.
Give your answer in the form \(a\sqrt{b}\), where \(a\) and \(b\) are integers and \(b\) is as small as possible.
(b)Write \(4\sqrt{ 275 }\) in the form \(a\sqrt{b}\), where \(b\) is as small as possible.
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2 marks
\(\sqrt{n} = 3\sqrt{ 7 }\)
Find the value of \(n\).
Answers
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(a) \(3\sqrt{ 6 }\)
(b) \(16\sqrt{ 2 }\) - \(245\)
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(a) \(5\sqrt{ 3 }\)
(b) \(3\sqrt{ 11 }\) -
(a) \(13 + 5\sqrt{ 13 }\)
(b) \(-1 -\sqrt{ 7 }\)
(c) \(30\) -
(a) \(4\sqrt{ 5 }\)
(b) \(\frac{ 9\sqrt{ 5 } }{ 5 }\) -
(a) \(12 - 3\sqrt{ 3 }\)
(b) \(6 + \sqrt{ 2 }\) -
(a) \(\sqrt{ 45 }\)
(b) \(\sqrt{ 3 }\) and \(\sqrt{ 5 }\) are not multiples of the same surd, so there is nothing to collect. In particular \(\sqrt{ 3 } + \sqrt{ 5 }\) is not \(\sqrt{ 8 }\): square roots do not add like that, since \(\sqrt{9} + \sqrt{16} = 3 + 4 = 7\) while \(\sqrt{9 + 16} = \sqrt{25} = 5\). -
(a) \(120\ \text{cm}^2\)
(b) \(14\sqrt{ 10 }\ \text{cm}\) -
(a) \(7\sqrt{ 3 }\)
(b) \(20\sqrt{ 11 }\) - \(63\)