Find the value of \sqrt{42−\sqrt{42−\sqrt{42−\ldots\ldots\ldots\ldots.}}

RRB Group-D Model Paper 20 with answers for online practice

Question : 48 of 100

Marks: +1, -0

Find the value of

√{42−√{42−√{42−………….}}}

Solution:

Let

√{42−√{42−√{42−………….}}}

=x
∴

√{42−√{42−√{42−………….}}}

√{42−x}

∴x=

√{42−x}

Squaring both sides,

x^2

=42−x

x^2

+7x−6x−42=0
x = -7, 6
Hence, 6 is the value of given expression as x cannot be negative.

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