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Question Number 40891 by abdo.msup.com last updated on 28/Jul/18
let x>0 and y>0 and  B(x,y) =∫_0 ^1 t^(x−1) (1−t)^(y−1) dt  1)prove that B(x,y)=B(y,x)  2)B(x+1,y)=(x/y) B(x,y+1)  3)B(x+1,y)=(x/(x+y))B(x,y)  4)B(x,n+1)=((n!)/(x(x+1)....(x+n)))  5)B(n,p) = (1/((n+p−1)C_(n+p−2) ^(p−1) ))
letx>0andy>0andB(x,y)=01tx1(1t)y1dt1)provethatB(x,y)=B(y,x)2)B(x+1,y)=xyB(x,y+1)3)B(x+1,y)=xx+yB(x,y)4)B(x,n+1)=n!x(x+1).(x+n)5)B(n,p)=1(n+p1)Cn+p2p1
Commented by maxmathsup by imad last updated on 03/Aug/18
1) B(x,y) = ∫_0 ^1  t^(x−1) (1−t)^(y−1) dt =_(1−t=u)   ∫_0 ^1 (1−u)^(x−1) u^(y−1)  du=B(y,x)  2)B(x+1,y) = ∫_0 ^1  t^x (1−t)^(y−1) dt  by parts u=t^x  and v^′ =(1−t)^(y−1)   B(x+1,y) =[−(1/y)(1−t)^y t^x ]_0 ^1  +∫_0 ^1  xt^(x−1)  (1/y)(1−t)^y dt  =(x/y) ∫_0 ^1   t^(x−1) (1−t)^y dt  = (x/y) B(x,y+1)
1)B(x,y)=01tx1(1t)y1dt=1t=u01(1u)x1uy1du=B(y,x)2)B(x+1,y)=01tx(1t)y1dtbypartsu=txandv=(1t)y1B(x+1,y)=[1y(1t)ytx]01+01xtx11y(1t)ydt=xy01tx1(1t)ydt=xyB(x,y+1)

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