Find the value of the limit x → 0 lim x e x − 1 .
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Nice way to derive the limit through first principles :)
In a similar manner, we can show that ( e x ) ′ = e x .
why you deleted ur solution , sir ? @Chew-Seong Cheong
let f(x)= e x , so
lim x → 0 x e x − 1 = lim x → 0 x − 0 f ( x ) − f ( 0 )
Observe that the limit above is the definition of derivative of f(x) at x=0, f'(x)= e x f'(0)=1
so, lim x → 0 x e x − 1 =1
nice solution, Khor! .)
Yeah but you are using the derivative of e^x as a fact while, in my opinion, the point is to prove it.
You are using what you want to prove 😅
By using Taylor series expansion of e^x.
For using Taylor series you have to know how to find the derivative of e x without using the definition, can you?
Well A common problem for JEE students And almost everyone does by Taylor series expansion ..
Use the expansion of e^x by taylor
For using Taylor series you have to know how to find the derivative of e x without using the definition, can you?
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x → 0 lim x e x − 1 = x → 0 lim x e i ( − i x ) − 1 = x → 0 lim x cos ( i x ) − i sin ( i x ) − 1 = x → 0 lim x cos ( i x ) − 1 − i x → 0 lim x sin ( i x ) = x → 0 lim sin ( i x ) ⋅ x ( cos ( i x ) + 1 ) sin ( i x ) − i 2 x → 0 lim i x sin ( i x ) = i x → 0 lim sin ( i x ) ⋅ i x ( cos ( i x ) + 1 ) sin ( i x ) + 1 ⋅ 1 i ⋅ 0 + 1 = 1