SSC CGL 9 Aug 2015 Shift 1 Paper

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Question : 128 of 200

Marks: +1, -0

The value of

1/{√7-√6}

-

1/{√6-√5}

+

1/{√5-2}

-

1/{√8-√7}

+

1/{3-√8}

is

7
0
1
5

Solution:

1/{√7-√6}

=

{√7+√6}/{(√7-√6)(√7+√6)}

(rationalising the denominator)
=

{√7+√6}/{7-6}

=

√7+√6

Similarly,

1/{√6-√5}

=

√6+√5

;

1/{√5+2}

=

√5 + 2

1/{√8-√7}

=

√8+√7

1/{3-√8}

= 3 +

√8

∴ Expression
=

(√7+√6)-(√5+√6)

+

(√5+2)-(√8+√7)+(3+√8)

=

√7+√6 - √6 - √5

+

√5

+ 2 -

√8

-

√7

+ 3 +

√8

= 2 + 3 = 5

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