Surds Flashcards
Leave the answer in a square root if it is a
Surd
Definition of a surd
A surd is a square root which cannot be written; its a non terminating decimal
What are the three forms of rational numbers
A whole number
A fraction
A terminating/recurring decimal
What are the two forms of irrational numbers
Never ending, non repeating decimals
Square/cube roots of non square/cube numbers
You …. multiply surds
Can
Eg (sqr)2 x (sqr)3 = (sqr)6
(Sqr)a/(sqr)b =
(Sqr)a/b
(Sqr)a + (sqr)b =
The same answer (cannot simplify)
[(a + (sqr)b) sq] =
( a + (sqr)b) ( a + (sqr)b)
a(sq) + 2a (sqr)b + b
You cant leave a …. In the denominator
Surd, therefore you must rationalise the denominator
If the question asks for an exact answer (length for example), you must give the answer
In the surd form (cm/m), only round to d.p.s if the question asks to do so
We rationalise a surd because
We don’t want the roots in the denominator
Rationalising just means multiplying the …… By the unwanted surd in the denominator
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