Question

How do you graph the function, label the vertex, axis of symmetry, and x-intercepts. `y=-x^2+4x+1`?

Answer 1

`D = d^2 = b^2 - 4ac = 16 + 4 = 20 = 4.(5)`
d = sqr5, and -sqr5
x-intercepts:
`x1 = -b/(2a) + d/(2a) = 2 - sqr5`
x2 = 2 + sqr5

Coordinate of vertex:
`x = -b/2a = 2` -> y = f(2) = -4 + 8 + 1 = 5
Axis of symmetry: `x = -b/(2a) = 2`