1. The problem asks to match the given graphs to one of the four quadratic functions:
A) $f(x) = x^2 + 2x + 1$
B) $f(x) = x^2 + 2x$
C) $f(x) = x^2 - 2x$
D) $f(x) = x^2 - 2x + 1$
2. Important: The vertex form of a parabola is $f(x) = a(x-h)^2 + k$ where $(h,k)$ is the vertex.
3. Let's find the vertex of each function by completing the square or using vertex formula $h = -\frac{b}{2a}$ for $ax^2 + bx + c$.
- For A) $x^2 + 2x + 1$:
$$h = -\frac{2}{2 \times 1} = -1$$
$$k = f(-1) = (-1)^2 + 2(-1) + 1 = 1 - 2 + 1 = 0$$
Vertex: $(-1,0)$
- For B) $x^2 + 2x$:
$$h = -\frac{2}{2} = -1$$
$$k = f(-1) = (-1)^2 + 2(-1) = 1 - 2 = -1$$
Vertex: $(-1,-1)$
- For C) $x^2 - 2x$:
$$h = -\frac{-2}{2} = 1$$
$$k = f(1) = 1^2 - 2(1) = 1 - 2 = -1$$
Vertex: $(1,-1)$
- For D) $x^2 - 2x + 1$:
$$h = -\frac{-2}{2} = 1$$
$$k = f(1) = 1^2 - 2(1) + 1 = 1 - 2 + 1 = 0$$
Vertex: $(1,0)$
4. The graphs both have vertex at $(-1,0)$, so the matching functions must have vertex $(-1,0)$.
5. From above, only function A) $x^2 + 2x + 1$ has vertex $(-1,0)$.
6. Therefore, the graph corresponds to function A).
Final answer: Function A) $f(x) = x^2 + 2x + 1$ matches the graph with vertex at $(-1,0)$.
Vertex Match 239A79
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