2. Sets A and B are both relations. Which relation is a function? * A: {(5,-2),(-2,5),(-5,2), (2, -5)} B: {(5,-2,),(-2,5),(5,2), (-5,2)}

List x1, x2, x3, x4 where xi is the left endpoint of the four equal intervals used to estimate the area under the curve of f(x) between x = 4 and x = 6. a 4, 4.5, 5, 5.5 b 4.5, 5, 5.5, 6 c 4.25, 4.75, 5.25, 5.75 d 4, 4.2, 5.4, 6