What are the vertex and x-intercepts of the graph of y= x2 - 4x - 21? Select
one answer for the vertex and one for the x-intercepts.
A. Vertex: (-2,-9)
B. x-intercepts: (3,0), (-7,0)
C. Vertex: (2, 13)
D. x-intercepts: (3,0), (7,0)
E. Vertex (2, -25)
F. x-intercepts: (-3,0), (7,0)

How to do this , and can some one explain

Let hh represent the number of hummingbirds and ss represent the number of sunbirds that must pollinate the colony so it can survive until next year. 6h+4s > 746h+4s> 74 this year, 88 hummingbirds pollinated the colony. what is the least number of sunbirds that must pollinate the colony to ensure that it will survive until next year?

Use the elimination method to solve the systems of equations.choose the correct ordered pair. 7x+4y=39