Question

find first two term of seqence sn=n2(n+1)

Answer 1

S₁ = T₁ = 1²(1 + 1) = 1 x 1 = 1

S₂ = T₁ + T₂ = 2²(2 + 1) = 2 x 3 = 6

1 + T₂ = 6

T₂ = 5

Answer 2

Sn = n2(n+1)

For S1, put n= 1

S1 = 1×2(1+1)

S1=2×2

S1= 4

Similarly

S2=2×2(2+1)

S2=4×3

S2=12

We know that S1 = A1

Therefore A1 =4

A2= S2-S1

A2=8

Therefore first two terms of AP are 4 and 8

a1=4 and d=4