A. (2/3, 9)
B. (2/5, 8)
C. (3/2, 6)
D. (5/2, 3)
The coefficient of xk in the expansion of E=1+(1+x)+(1+x)2+……..+(1+x)n is
C0+3.C1+5.C2+……..+(2n+1).Cn =
The coefficient of x7 in (1+2x+3x2+4x3+……..∞)-3 is
C1/C0+2. C2/C1+3.C3/C2+....n. Cn/Cn-1=
Middle term in the expansion of (2x-3/x)15is