SSC CHSL 20 Dec 2015 Shift 2 Paper

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Question : 116 of 200

Marks: +1, -0

The value of

{3√7}/{√5+√2} -{5√5}/{√2+√7}+{2√2}/{√7+√5}

1
0
$2√3$
$√7$

Solution:

Expression :

{3√7}/{√5+√2} -{5√5}/{√2+√7}+{2√2}/{√7+√5}

=

({3√7}/{√5+√2} ×{√5-√2}/{√5-√2})

-( {5√5}/{√2+√7}×{√7-√2}/{√7-√2})

+({2√2}/{√7+√5} ×{√7-√5}/{√7-√5})

Using,

(a + b)(a − b) = a^ 2 − b^2

=

{3√7( √5− √2)}/{ 5−2 }

- {5√ 5( √7− √2)} /{7-2}

+ {2√2 ( √7−√ 5)}/{7-5}

=

{3√7( √5− √2)}/{ 3 }

- {5√ 5( √7− √2)} /{5}

+ {2√2 ( √7−√ 5)}/{2}

=

√7(√ 5 − √2) − √5( √7 −√ 2)

+√ 2( √7 − √5)

=

√35 − √14 − √35

+ √10 + √14 − √10 = 0

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