Which rule explains why these triangles are congruent ?

What's the difference between: x≥0 and nonnegative integer. ?

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

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