The coefficient of the middle term in the binomial expansion in powers of x of (1 +αx)4 and of (1−αx )6 is the same if α equals
-5/3
3/5
-3/10
-3/10
The coefficient of xn in expansion of (1+x)(1-x)n is
(n-1)
(-1)n(1-n)
(-1)n-1(n-1)2
(-1)n-1(n-1)2
Let T be the rth term of an A.P. whose first term is a and the common difference is d. If for r some positive integers m, n, m ≠ n, Tm = 1/n and Tn = 1/m, then a-b equals
0
1
1/mn
1/mn
The sum of series
B.
Let α, β be such that π < α - β < 3π. If sinα + sinβ = -21/65 and cosα + cosβ = -27/65, then the value of cos α-β/2 is
6/65
6/65
If then the difference between the maximum and minimum values of 2 u is given by
2(a2 + b2)
2(a2-b2)
(a+b)2
(a+b)2
The sides of a triangle are sinα, cosα and for some 0 < α < π/2 . Then the greatest angle of the triangle is
60o
120o
360o
360o
A person standing on the bank of a river observes that the angle of elevation of the top of a tree on the opposite bank of the river is 60o and when he retires 40 meters away from the tree the angle of elevation becomes 30o. The breadth of the river is
20 m
30 m
40 m
40 m