math
posted by Deborah .
Determine whether the given quadratic function has a minimum value or maximum value. Then find the coordinates of the minimum or maximum point.f(x) = x2 + 2x  9

since the coefficient of x^2 is positive, we know the parabola opens upward, so it minimum.
The vertex of the parabola is at x = 1, so plug that in to get y.
Or, complete the square:
y = x^2+2x+1  8
y = (x+1)^2  8
y+8 = (x+1)^2
Now you can just read off the coordinates.