RRB Junior Engineer Stage 1 Model Papers 6

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Question : 5 of 99

Marks: +1, -0

If

5a+1/{2a}=5

,the value of

9a^2+1/{25a^2}

is

$34/5$
$39/5$
$42/5$
$52/5$

Solution:

5a+1/{3a}=5

On multiplying by

3/5

,

3a+1/{5a}=5×3/5=3

On squaring,

9a^2+1/{25a^2}+2×3a×1/{5a}=9

⇒9a^2+1/{25a^2}

=9-6/5={45-6}/5=39/5

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