Question 5 • Advanced Algebra: Concepts and Connections
A function has an inverse that is also a function when it is one-to-one: each output must come from only one input. The rule m(x) = −7x is one-to-one, since different x-values produce different outputs, so its inverse is m⁻¹(x) = −x/7. The other choices are not one-to-one; for example, x and −x give the same output for |x| and x² + 3.
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