Metamath Proof Explorer


Theorem reeftcl

Description: The terms of the series expansion of the exponential function at a real number are real. (Contributed by Paul Chapman, 15-Jan-2008)

Ref Expression
Assertion reeftcl
|- ( ( A e. RR /\ K e. NN0 ) -> ( ( A ^ K ) / ( ! ` K ) ) e. RR )

Proof

Step Hyp Ref Expression
1 reexpcl
 |-  ( ( A e. RR /\ K e. NN0 ) -> ( A ^ K ) e. RR )
2 faccl
 |-  ( K e. NN0 -> ( ! ` K ) e. NN )
3 2 adantl
 |-  ( ( A e. RR /\ K e. NN0 ) -> ( ! ` K ) e. NN )
4 1 3 nndivred
 |-  ( ( A e. RR /\ K e. NN0 ) -> ( ( A ^ K ) / ( ! ` K ) ) e. RR )