Quadratic inequalities

1.Let k=(2x-5)/(x^2+6). Find the range of values of k for REAL VALUES of x
(請問all real values of x 同 real values of x 有何分別?)

2. Find the range of real values of k if (3k-1)x^2-2x+(k-1)less/equal to 0 for all realvalues of x

3. Let f(x)=(1-2m)x^2+2(m-4)x+(4-m), where m is a real number. Find the range of values of m such that
i) f(x)>0 for all real values of x
ii) f(x)<0 for all real values of x

4.想問如果條題目f(x), 係for all real values of x,即係咩意思?個discriminant 是否一定係less than 0?