To determine which graph could represent a square root function, we need to consider the characteristics of square root functions.
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Domain: The domain of a square root function \( f(x) = \sqrt{x} \) is \( x \geq 0 \). This means the graph will only exist in the right half of the coordinate plane (first quadrant), and will not have any negative x-values.
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Shape: The graph of a square root function is a curve that starts from the origin (0,0) and rises slowly, becoming less steep as x increases. It looks like half of a sideways parabola.
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Y-values: The only y-values produced by a square root function are non-negative, as square roots cannot yield negative outputs.
Based on these characteristics, we can analyze the provided graph descriptions:
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Graph 1 (S-shaped curve): This does not represent a square root function due to its S-shaped nature, indicating it likely represents some other function.
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Graph 2 (concave up parabola): While this graph may resemble the shape of a square root function in one part, parabola graphs can extend in both directions and may have negative y-values, so it doesn't represent a square root function directly.
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Graph 3 (straight line): A straight line could represent a linear function, not a square root function, so it's not the correct answer.
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Graph 4 (curve in the first quadrant): This graph fits the characteristics of a square root function. It is in the first quadrant, indicating non-negative x and y values, and likely has the correct shape (curving upwards but flattening out as x increases).
Given this analysis, Graph 4 is the one that could represent the graph of a square root function.