A. (x2+a2)n

B. (x2-a2)n

C. 1/2[(x+a)2n+(x-a)2n]

D. 1/2[(x+a)2n-(x-a)2n]

If the coefficients of (2r+1)^{th} term and (4r+5)^{th} term in the expansion of (1+x)^{10} are equal then r=

If the 3^{rd}, 4^{th} and 5^{th} terms of (x+a)^{n} are 720, 1080 and 810 respectively then (x,a,n)=

x^{n}-1 is divisible by x-k. Then the least +ve integral value of K is

The point which divides the line segment joining the points( 1,-1,2), (2,3,7) in the ratio -2:3 is

The first three terms in the expansion of (1+x+x^{2})^{10} are