Question

va rog repede am nevoie​

Answer 1

Explicație:

n(n+1)+(n+1)(n+2)=72=>

(n+1)(n+n+2)=72=>

(n+1)*2(n+1)=72=>

(n+1)²=36=>

n+1=6 sau n+1=-6 =>

n=5 sau n=-7

Dar cum n€N => S€{5}

(n+1)(n+2)+(n+2)(n+3)=162=>

(n+2)(n+1+n+3)=162=>

(n+2)(2n+4)=162=>

(n+2)*2(n+2)=162=>

(n+2)²=81 =>

n+2=9 sau n+2=-9=>

n=7 sau n=-11

n€N => S€{7}