Latest TCS Aptitude Question SOLUTION: The sequence {A(n)} is defined by A(1) = 2 and A(n+1)=A(n)+2*n what is the value of A(100)? A. 9902 B. 9900 C. 10100 D. 9904

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(#M40116972) TCS Numerical Ability question Series and sequences Keep an EYE

The sequence {A(n)} is defined by A(1) = 2 and A(n+1)=A(n)+2*n what is the value of A(100)?

A. 9902
B. 9900
C. 10100
D. 9904

Asked In TCS Emanuel Abhishek Murmu (9 years ago)

Solved Asit Ranjan Raman Read Solution (3)

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Asit Ranjan Raman  (9 years ago) Best Solution

n=1, A(1)=2
n=2, A(2)=A(1+1)=A(1)+2*1=2+2=4
n=3, A(3)=A(2+1)=A(2)+2*2=4+4=8
n=4, A(4)=A(3+1)=A(3)+2*3=8+6=14
if n=1, A(1)=2
if n=2, A(2)=4, i.e 2*2-0=4
if n=3, A(3)=8, i.e 3*3-1=8
if n=4, A(4)=14 i.e 4*4-2=14
..........
if n=100, A(100)=100*100-98=10000-98=9902
ans=9902

.

Is this solution Helpfull? Yes (18) | No   

raju  (9 years ago)

Solve recurrence relation
finally
A(1)+2*(1+2+3...99)
which is 2+2*99*100/2
9902ans

Is this solution Helpfull? Yes (9) | No   

raju  (9 years ago)

A(1)=2
so A(2)=A(1)+2*1
which is 4
similarly
A(3)=A(2)+2*2
4+4=8
then
A(4)=A(3)+2*3
8+6=14

Is this solution Helpfull? Yes (1) | No (1)  

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