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Question Number 184880 by mathlove last updated on 13/Jan/23
lim_(x→(1/π))   ((π^(−1) −x)/((1−(xπ)^2 )/π^2 ))=?
$$\underset{{x}\rightarrow\frac{\mathrm{1}}{\pi}} {\mathrm{lim}}\:\:\frac{\pi^{−\mathrm{1}} −{x}}{\frac{\mathrm{1}−\left({x}\pi\right)^{\mathrm{2}} }{\pi^{\mathrm{2}} }}=? \\ $$
Answered by aba last updated on 13/Jan/23
lim_(x→(1/π)) ((π^(−1) −x)/((1−(πx)^2 )/π^2 ))=lim_(x→(1/π)) ((π^2 (π^(−1) −x))/(1−(πx)^2 ))=lim_(x→(1/π)) ((π(1−πx))/(1−(πx)^2 ))=lim_(x→(1/π)) (π/(1+πx))=(π/2)
$$\underset{{x}\rightarrow\frac{\mathrm{1}}{\pi}} {\mathrm{lim}}\frac{\pi^{−\mathrm{1}} −\mathrm{x}}{\frac{\mathrm{1}−\left(\pi\mathrm{x}\right)^{\mathrm{2}} }{\pi^{\mathrm{2}} }}=\underset{{x}\rightarrow\frac{\mathrm{1}}{\pi}} {\mathrm{lim}}\frac{\pi^{\mathrm{2}} \left(\pi^{−\mathrm{1}} −\mathrm{x}\right)}{\mathrm{1}−\left(\pi\mathrm{x}\right)^{\mathrm{2}} }=\underset{{x}\rightarrow\frac{\mathrm{1}}{\pi}} {\mathrm{lim}}\frac{\pi\left(\mathrm{1}−\pi\mathrm{x}\right)}{\mathrm{1}−\left(\pi\mathrm{x}\right)^{\mathrm{2}} }=\underset{{x}\rightarrow\frac{\mathrm{1}}{\pi}} {\mathrm{lim}}\frac{\pi}{\mathrm{1}+\pi\mathrm{x}}=\frac{\pi}{\mathrm{2}} \\ $$

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