Question

Calcule; a) A7, 3 b) A11, 2 c) a5, 1 d) A5, 5

Answer 1

A-7!/(7-3)!
7!/4!
7*6*5*4!/4!
7*6*5=210

B-11!/(11-2)!
11!/9!
11*10*9!/9!
11*10=110

C-5!/(5-1)!
5!/4!
5*4!/4!
5

D-5!/(5-5)!
5!/0!
5*4*3*2*1!/1!
5*4*3*2=60