Which of the following functions

MATHEMATICS · Single correct · A Level · Mathematics · Algebra and Functions · Algebra and Functions

Problem

Which of the following functions, with the indicated domain, is NOT one–one? (a) f2:R→R,  f2(x)=exf_2:\mathbb{R}\to\mathbb{R},\;f_2(x)=e^{x} (b) f4:R→R,  f4(x)=x2+1f_4:\mathbb{R}\to\mathbb{R},\;f_4(x)=x^{2}+1 (c) g:[0,∞)→R,  g(x)=x2+1g:[0,\infty)\to\mathbb{R},\;g(x)=x^{2}+1 (d) f3:(0,∞)→R,  f3(x)=ln⁡xf_3:(0,\infty)\to\mathbb{R},\;f_3(x)=\ln x

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