SSC CGL Model Paper 16

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Question : 63 of 100

Marks: +1, -0

If

√ {5 x -6} + √{5x + 6} = 6,

then what is the value of x ?

-4
0
2
4

Solution:

√ {5 x -6} + √{5x + 6} = 6

On squaring both sides,

5 x -6 + 5x + 6 + 2√{25x^2-36}=36

⇒

10x + 2√{25x^2-36}=36

⇒

10x - 3 6 =-2√{25x^2-36}

⇒

100x^2 +1296 - 720x

= 4 (25x^2 -3 6 )

⇒

25x^2 + 324 - 180x

= 25x^2 -3 6

⇒

180x =360

∴

x =2

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