fx=1e-x হলে Limh→0 f(x+h)-f(x)h এর মান কোনটি?
A
e-x
B
1ex
C
ex
D
1e-x
Correct Answer: ex
limx→0{f(x+h)-f(x)/h =lim {x→0(1/e-x-h-1/e-x)/h} =lim {x→0(ex×eh-ex)/h} =lim {ex x→0(eh-1)/h} =ex× lim { x→0(eh-1)/h} =ex