factorial

[azure vapor]

Can somebody help me
Even with the solution i can’t understand

[azure vapor]

How -k! Is transformed en -k ?

Tk u

[fluid island]

?

[marsh isle]

k+1 copies of k! - 1 copy of k!

[safe dragon]

$(k+1) \times k! - k! = (k+1) \times k! - 1\times k! = [ (k+1) -1 ] \times k! = [ k ] \times k!$

[hearty python]

Pfötchen

[hearty python]

ItsDaivikDUH

$(k+1) \times k! - k! = (k+1) \times k! - 1\times k! = [ (k+1) -1 ] \times k! = [ k ] \times k!$

ItsDaivikDUH