Doubt in limits

[Kshitijranaw]

@AshWin
@ThirdJuly
@Abhinav.08
@Sanjay_S
@mihir

pls help guys
ans is 43
thank you

[Electric_arch]

Evaluate this integral to get a=27. b=16
a+b=43
ab=432

[Ldrago]

Use Incomplete Stirling approximation
ln(n!)=nln(n) - n