Respuestas

2012-09-12T07:48:29+02:00

C(x+2),x = 15

(x+2)!/((x+2-x)!*x!)=15

(x+2)!/(2!*x!)=15

x!*(x+1)*(x+2)/(2!*x!)=15

(x+1)*(x+2)=30=5*6

x+1=5-->x=4