Graph of a quadratic function

A function is shown.

f(x) = x² + 2x - 1

Which graph represents this function?
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In the function f(x) = x² + 2x - 1,
- the constant term, -1, is the y-intercept of the graph
- the x² term is positive, meaning the parabola opens upward
- also, the x-coordinate of the vertex is 
-b          -2
----  =  -----   =  -1 is the x-coordinate of the vertex
2a          2(1)

y-intercept is -1
parabola opens up
x-coordinate of vertex is -1

Graph C.)  {the one on the top right}

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