A. 5
B. 6
C. 7
D. none
If the third term in the expansion of (1/x+ xlog10 x)5 is 1, then x=
2.C0+22.C1/2+23.C3/3+……..+2n+1.Cn/n+1 =
If n is odd then C02-C12+C22-……….+(-1)n Cn2 =
Coefficient of x50 in (1+x)1000+2x(1+x)999+3x2(1+x)998+……..+1001x1000 is
The midpoint of the line segment joining (2,3,-1), (4,5,3) is
The coefficient of x6 in (1+x+x2+x3+x4+x5)6 is
The ratio of the coefficient of x15 to the term independent of x in (x2+2/x)15 is
The number of non zero terms in the expansion of (a+b)20 – (a-b)20 is
mCr+ mCr-1nC1+mCr-2. nC2+………..+ nCr =
Sum of the last 20 coefficients in the expansion of (1+x)39, when expanded in ascending powers of x, is