For a positive integer is expanded in increasing powers of x. If three consecutive coefficients in this expansion are in the ratio, 2 : 5 : 12 , then n is equal to _____
If the variance of the terms in an increasing A.P. b1, b2, b3, ... , b11 is 90, then the common difference of this A.P. is
Ans : 3
Let the position vectors of points 'A' and 'B' be , respectively. A point 'P' divides the line segment AB internally in the ratio : 1 ( > 0). If O is the origin and then is equal to