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There are several ways to find the vertex and graph a quadratic function. One easy way is to realize that in the general case
the vertex is at
the coefficient of x is zero, so the vertex is at x=0. When x = 0, y = -4, so the vertex is at (0, -4).
The graph opens upward, since the coeffient of x^2 is positive. It would open downward if the coefficient of x^2 is negative.
The y-intercept is where x=0, which is at the point (0, -4).
The x-interecepts are where y=0, which are at
or x=2 and at x=-2.