# How do you write y=-x^2-2x+3 in vertex form and identify the vertex, y intercept and x intercept?

May 19, 2015

y = -x^2 - 2x + 3

x of vertex: x = (-b/2a) = 2/-2 = -1

y of vertex: f(-1) = -1 + 2 + 3 = 4

Vertex form: $f \left(x\right) = - {\left(x + 1\right)}^{2} + 4.$

Check by developing: f(x) = -(x^2 + 2x + 1) + 4 = -x^2 - 2x + 3. OK

x-intercepts: y = 0.
Since a + b + c = 0, one real root is $x = 1$ and the other is
$x = \frac{c}{a} = - 3$