The coefficient of `a^8b^4c^9d^9` in `(a b c+a b d+a c d+b c d)^(10)` is `10 !` b. `(10 !)/(8!4!9!9!)` c. `2520` d. none of these

Find the coefficient of a^3b^4c in the expansion of (1+a-b+c)^9dot

The coefficient of t^4 in ((1-t^6)/(1-t))^3 (a) 18 (b) 12 (c) 9 (d) 15

Let the positive numbers a , b , c , d be in AP. Then a b c ,a b d ,a c d ,b c d are

Among 10 persons, A, B, C are to speak at a function. The number of ways in which it can be done if A wants to speak before B and B wants to speak before C is a. 10 !//24 b. 9!//6 c. 10 !//6 d. none of these

If a ,b ,c in R^+t h e n(a+b+c)(1/a+1/b+1/c) is always (a) geq12 (b) geq9 (c) lt=12 (d)none of these

If a, b, c, d are in G.P., then (a + b + c + d)^(2) is equal to

If a ,b ,c ,d in R^+ and a ,b ,c,d are in H.P., then (a) a+d > b+c (b) a+b > c+d (c) a+c > b+d (d)none of these

a ,b ,c x in R^+ such that a ,b ,a n dc are in A.P. and b ,ca n dd are in H.P., then a b=c d b. a c=b d c. b c=a d d. none of these

The number of real solutions of the equation (9//10)^x=-3+x-x^2 is a. 2 b. 0 c. 1 d. none of these

If A=[[a+i b, c+i d],[-c+i d, a-i b]]a n da^2+b^2+c^2+d^2=1,t h e nA^(-1) is equal to a. [[a+i b,-c+i d],[-c+i d, a-i b]] b. [[a-i b,-c-i d],[-c-i d, a+i b]] c. [[a+i b,-c-i d],[-c+i d, a-i b]] d. none of these