Let S be the set of all persons living in Delhi. We say that x, y in S are related if they were born in Delhi on the same day. Which one of the following is correct ?
The relation is an equivalent relation
The relation is not reflexive but it is symmetric and transitive
The relation is not symmetric but it is reflexive and transitive
The relation is not transitive but it is reflexive and symmetric
Let A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}. Then, the number of subsets of A containing two or three elements is
45
120
165
330
If the difference between the roots of the equation x2 + kx + 1 = 0 is strictly less than , then k can be any element of the interval
( - 3, 3)
None of the above
If the roots of the equation x2 + px + q = 0 are in the same ratio as those of the equation x2 + lx + m = 0, then which one of the following is correct ?
p2m = l2q
m2p = l2q
m2p = q2l
m2p2 = l2q
Three-digit numbers are formed from the digits 1, 2 and 3 in such a way that the digits are ot repeated. What is the sum of such three-digit numbers ?
1233
1322
1323
1332
What is the sum of the serie 0.3 + 0.33 + 0.333 +... n terms
A.
If the sum of m terms of an AP is n and the sum of n terms is m, then the sum of (m + n) terms is
mn
m + n
2(m + n)
- (m + n)