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MathematicsSequence & SeriesMeans / inequalityHard2 minPYQ_2015
MathematicsHardmatching list
Column IColumn II

 

 

(A)In R2 , if the magnitude of the projection vector of the vector αi^+βj^  on 3 i^+ j^ is 3 and if α=2+ 3 β, then possible value (s) of |α| is (are)P1
(B)Let a and b be real numbers such that the function fx= -3ax2-2,x<1bx+a2,x 1 is differentiable for all xR. Then possible value (s) of a is (are)Q2
(C)Let ω 1 be a complex cube roots of unity. If 3-3ω+2ω24n+3 + 2+3ω-3ω24n+3+ -3+2ω+3ω24n+3=0 then possible value (s) of n is (are)R3
(D)Let the harmonic mean of two positive real numbers a and b 4. If q is a positive real number such that a, 5, q, b is an arithmetic progression, then the value (s) of |q – a| is (are)S4
  (T)5

Options:

Answer:
C
Solution:

AAs3α+β2=33α+β=23...(i)
And, alsoα=2+3β...(ii)
Solving (i) & (ii), we get
23+4β=±23
β=0, -3
So,α=2and-1
i.e,α=2, 1
(B)Here-3a-2=b+a2...(i)
And-6a=b...(ii)
Solving (i) and (ii),
-3a-2=-6a+a2
a2-3a+2=0
a=1, 2
CHere,3-3ω+2ω24n+31+ω4n+3+ω24n+3 
3-3ω+2ω24n+31+ω4n+ω8n=0
So,n=1, 2, 4, 5
Dq-a=2d
Letq-q=α, d=α2
a=5-α2, b=a+3α2=5+α
Now,aba+b=2
5-α25+α5-α2+5+α=2
α=5, -2
α=5, 2

Stream:JEE_ADVSubject:MathematicsTopic:Sequence & SeriesSubtopic:Means / inequality
2mℹ️ Source: PYQ_2015

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