What is the vertex of the graph. is it a maximum or minimum ​

In the 30-60-90 triangle below side s has a length of and side r has a length

Evaluate the expression for the given value of the variable 7a - 4a for a =8

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