SSC
Government Jobs Exams
Numerical Ability
Arithmetic
sqrt (6+ sqrt(6+ sqrt (6+...))) is equal to
a) 2 b) 5 c) 4 d) 3
Read Solution (Total 5)
-
- let y=sqrt(6+sqrt(6+sqrt(+...)))
y=sqrt(y+6)
squaring both side
y2=y+6
y=3 - 12 years agoHelpfull: Yes(4) No(0)
- let, y=√(6+√(6+√(6+...))) ---- (i)
now,
as there are lots of(infinite times) √6 is added, so if we leave 1 of √6 (let from rightmost side), there wouldn't be any loss in sum. and,
now, the above expression become (same as above):
y= √(6+√(6+√(6+...))) ---- (ii)
now,
put the value of eqn(ii) in eqn(i)(leaving 1st √6 at its place), we get,
y= √(6+y)
squaring both side, y^2= 6+y or, y^2 -y -6=0.
On solving , we get y=-2,3 => y = +3 (as √ can't be negative) --- Ans
- 12 years agoHelpfull: Yes(1) No(0)
- sqrt (6+ sqrt(6+ sqrt (6+...)))=x
=> x=sqrt(6+x)
=> x^2=6+x
=>x^2-x-6=0
=>x^2-3x+2x-6=0
=>(x-3)(x+2)=0
=>x=-2,3
neglect -2
Ans=3 - 12 years agoHelpfull: Yes(0) No(0)
- sqrt(6+x)=x
x=-2,3
hence x=3 is ans - 12 years agoHelpfull: Yes(0) No(0)
- d=3 is solution
- 11 years agoHelpfull: Yes(0) No(0)
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