If a is a 6 × 6 matrix with dim(nulla) = s and dim(ima) = t, which of the following are possible values for s and t?
a) s = 0, t = 5
b) s = –3, t = 9
c) s = 2, t = 3
d) s = 6, t = 0

Me solve this problem, and someone clearly explain to me how to solve it.1.) use the value of the discriminant to determine if the given trinomials has 2 real solutions, 1 real solution, or no real solutions. a.  x2  − 4x  − 7 = 0b. 4r2  + 11r  − 3 = 0c. 3m2  + 7 = 0d.  t2  + 2t  + 1 = 0