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Basic of Logarithms
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The rationalising factor of $2\sqrt 3 - \sqrt 7 $ is
A
$\sqrt 3 + \sqrt 7 $
B
$2\sqrt 3 + \sqrt 7 $
C
$\sqrt 3 + 2\sqrt 7 $
D
None of these
Solution
(b) $(2\sqrt 3 – \sqrt 7 )\,(2\sqrt 3 + \sqrt 7 ) = 12 – 7 = 5$ (a rational)
$\therefore$ Rationalising factor $=2\sqrt 3 + \sqrt 7 $
Standard 11
Mathematics