Lecture 1 - UH

Examples and Counter-Examples Examples 3. • f(x) = 3x−5 is 1-to-1. • f(x) = x2 is not 1-to-1. • f(x) = x3 is 1-to-1. • f(x) = 1 x is 1-to-1. • f(x) = xn −x, n > 0, is not 1-to-1. Proof. • f(x 1) = f(x 2) ⇒ 3x 1 − 5 = 3x 2 − 5 ⇒ x 1 = x 2.In general, f(x) = ax−b, a 6= 0, is 1-to-1.

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An operational definition is how we (the researcher ...

a) 1 hour exposure b) no exposure c) depression 2) Does age of child (4, 5, or 6) influence when children can learn to read? a) age of child b) level of reading 3) Time reading on exam performance a) time reading b) exam performance