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)

C. Vertex (2,13)

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.