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Question Number 157104 by zakirullah last updated on 19/Oct/21

prove lim_(△x→0) ((e^(△x) −1)/(△x))=1

$${prove}\:\underset{\bigtriangleup{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\frac{{e}^{\bigtriangleup{x}} −\mathrm{1}}{\bigtriangleup{x}}=\mathrm{1} \\ $$

Answered by puissant last updated on 19/Oct/21

lim_(Δx→0) ((e^(Δx) −1)/(Δx)) ∼lim_(Δx→0) ((1+Δx−1)/(Δx))=1

$$\underset{\Delta{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\frac{{e}^{\Delta{x}} −\mathrm{1}}{\Delta{x}}\:\sim\underset{\Delta{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\frac{\mathrm{1}+\Delta{x}−\mathrm{1}}{\Delta{x}}=\mathrm{1} \\ $$

Commented by zakirullah last updated on 20/Oct/21

thanks alot

$${thanks}\:{alot} \\ $$

Answered by Fresnel last updated on 20/Oct/21

lim_(Δx⇢0) ((e^(Δx) −1)/(Δx))=lim_(Δx⇢0) ((e^(Δx) −e^0 )/(Δx−0))=e^0 =1 becausef′(x)=e^(x ) for f(x)=e^x  and lim_(x⇢0) ((f(x)−f(0))/(x−0))=f′(0).

$$\mathrm{li}\underset{\Delta{x}\dashrightarrow\mathrm{0}} {\mathrm{m}}\frac{{e}^{\Delta{x}} −\mathrm{1}}{\Delta{x}}={li}\underset{\Delta{x}\dashrightarrow\mathrm{0}} {{m}}\frac{{e}^{\Delta{x}} −{e}^{\mathrm{0}} }{\Delta{x}−\mathrm{0}}={e}^{\mathrm{0}} =\mathrm{1}\:{becausef}'\left({x}\right)={e}^{{x}\:} {for}\:{f}\left({x}\right)={e}^{{x}} \:{and}\:{li}\underset{{x}\dashrightarrow\mathrm{0}} {{m}}\frac{{f}\left({x}\right)−{f}\left(\mathrm{0}\right)}{{x}−\mathrm{0}}={f}'\left(\mathrm{0}\right). \\ $$

Commented by zakirullah last updated on 20/Oct/21

great sir!

$${great}\:{sir}! \\ $$

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