Question

Liberty Maths Paper Set 2022


For a series, Sn - 2Sn‐¹ + Sn-² = ? (n> 2)

Answer 1

Answer:

We know that, T

n

=S

n

−S

n−1

, where S

n

is sum of first n terms

S

n

−2S

n−1

+S

n−2

=S

n

−S

n−1

−S

n−1

+S

n−2

=(S

n

−S

n−1

)−(S

n−1

−S

n−2

)

=T

n

−T

n−1

=d

Hence, S

n

−2S

n−1

+S

n−2

=d

so answer is d