A function is considered one-to-one if it passes the horizontal line test, meaning that no horizontal line intersects the graph of the function more than once. Let's analyze each of the given functions:
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r(x) = (x + 8)² - 2: This is a quadratic function, which is not one-to-one because it is a parabola that opens upwards. A horizontal line can intersect it at two points.
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c(x) = -6x - 1: This is a linear function with a non-zero slope. Linear functions are one-to-one because any horizontal line will intersect it at most once.
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m(x) = |4x + 20| + 6: The absolute value function is not one-to-one because it can take the same value for different inputs (e.g., both x = -10 and x = 10 yield the same result for this function).
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t(x) = -2 - x⁴: This function is not one-to-one as well because it is a quartic function that opens downwards and can also potentially repeat values for different x.
Thus, the only one-to-one function among the options provided is:
c(x) = -6x - 1.