Q.

Let for x∈ℝ, S0(x)=x,Sk(x)=Ckx+k∫0xSk-1(t) dt, where C0=1, Ck=1-∫01Sk-1(x) dx, k=1,2,3,… Then S2(3)+6C3 is equal to _______ .    [2023]


Ans.

(18)

Given, Sk(x)=Ckx+k∫0xSk-1(t) dt  ...(i)

Put k = 2 and x = 3 in (i),

S2(3)=C2(3)+2∫03S1(t) dt  ...(ii)

Put k = 1 in (i),

S1(x)=C1x+∫0xS0(t)dt=C1x+∫0xt dt   [∵S0(x)=x]

=C1x+x22

Put S1(t)=C1t+t22 in (ii),

S2(3)=C2(3)+2∫03(C1t+t22)dt

=3C2+2[C1t22+t36]03=3C2+2[C1(92)+(276)]

=3C2+9C1+9  
 

Given, Ck=1-∫01Sk-1(x) dx                           ...(iii)

Put k = 1 in (iii),

C1=1-∫01S0(x)dx=1-∫01xdx=1-(x22)01=12

Put k = 2 in (iii),

C2=1-∫01S1(x)dx=1-∫01(C1x+x22)dx

=1-[C1x22+x36]01 =1-[12×12+16] =1-[14+16]=1-512=712

Put k = 3 in (iii), C3=1-∫01S2(x)dx

Put k = 2 in (i), S2(x)=C2x+2∫0xS1(t) dt=C2x+C1x2+x33

So, C3=1-∫01(C2x+C1x2+x33)dx

=1-[C2x22+C1x33+x412]01

=1-712×12-12×13-112=1-724-16-112

=24-7-4-224=1124

S3(3)+6C3=3C2+9C1+9+6C3

=3×712+9×12+9+6×1124=74+92+9+114

=7+18+36+114=724=18