38. define a = {(a, b) e r2 : (y +x*) dx +(ax + by ) dy = 0 is exact }, then a) la) a is non-empty (b) a=1 lc) a is similar to the set of transcendental numbers

38. Define A = {(a, b) e R2 : (y +x*) dx +(ax + by ) dy = 0 is exact }, then a) la) A is non-empty (b) A=1 lc) A is similar to the set of transcendental numbers over Q (d) A is similar to the set of natural numbers