The Total solution for NCERT class 6-12
f:R –> R is defined by f (x) = 3x(a) f(x1) = 3x1, f(x2) = 3x2=> f(x1) = f(x2)=> 3x1 = 3x2=> x1 = x2=> f is one-one(b) for every member y belonging to co-domain has pre-image x in domain of f.∵ y = 3x=>f is ontof is one-one and onto. Option (a) is correct.