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There are many functions, the graphs of which appear as waves on X-axis of Cartesian plane, with ever increasing amplitude as $x$ approaches $–\infty$. eg. $y=x^n \sin(x)\cos(x)$ Can you provide me with some more examples of such functions?

tarit goswami
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2 Answers2

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Functions like$$e^{kx} \sin bx$$ and $$e^{kx} \cos bx$$ with different values of $k$ and $b$ are other examples of wavy functions.

  • Can you please provide examples where the amplitude increases as x approaches –∞? – Sumant Chopde Aug 27 '18 at 05:29
  • $e^{-2x} cos x$ is such a function. When you let $k<0$ the amplitude goes to infinity as $x\to -\infty$ – Mohammad Riazi-Kermani Aug 27 '18 at 05:33
  • @SumantChopde. If you replace $e^{kx}$ with $\cosh(kx) = \frac12(e^{kx}+e^{-kx})$ or $\sinh(kx) = \frac12(e^{kx}-e^{-kx})$ then you get a "wavy function" with an amplitude that tends to infinity at both ends, both as $x \to +\infty$ and as $x \to -\infty.$ – md2perpe Aug 27 '18 at 05:35
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Some examples:

  1. $\frac12(e^x + e^{-x}) \sin x$

  2. $|x| \sin x$

  3. $\ln|x| \sin x$

  4. $\sqrt{1+x^2} \sin x$

  5. $e^{e^x+e^{-x}} \sin x$

md2perpe
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