A. ∑n=2∞ (n-1) xn-2
B.= ex
C. = f (x) =( 1/4 ) + (2x / 42 ) + ( 3x2 / 43 ) + ( 4x3/ 44 ) + ( 5x4/ 45) +....
Then f (x) =( 1/4 ) + (2x / 42 ) + ( 3x2 / 43 ) + ( 4x3/ 44 ) + ( 5x4/ 45) +....
Hence ∫02 f(x) d x = ∫02 ( 1/4 ) d x + ∫02 (2x / 42 ) d x + ∫02 ( 3x2 / 43 ) d x +....=
= 1/2 + 1/4 + 1/8 + 1/16 +.... = (1/2) /[ 1 -(1/2) ] = 1