Select all of the expressions that are equivalent to 4√5.

•2√20
•6½ − 5½
•3×5½ + 5½
•4 × 5½
•2√10
•3 × 5½

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