2+2 bằng bao nhiêu vậy mọi người

Acircle has a diameter will endpoints of (-2,8) and (6, 4). what is the center of the circle

A. 90 degrees b. 45 degrees c. 30 degrees d. 120 degrees

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