If: is defined by f (x) = x - [x], where[x] is the greatest integer not exceeding x, then the set of discontinuous of f is
the empty set
R
Z
N
If y = acos(log (x)) + bsin (log(x)), where a, b are parameters, then xy" + xy' is equal to
y
- y
2y
- 2y
The two curves x = y2, xy = a2 cut orthogonally at a point, then a2 is equal to
1
2
B.