Question

Daca 1+3+5+...+13=x la puterea adoua care e valoare lui x​

Answer 1

1+3+5+…+13 = x^2

1+3+5+…+13 = suma lui Gauss
intai aflam numarul de termeni
(13-1):2+1
12:2+1
6+1
=7 termeni

1+3+5+…+13= (1+13) x 7 :2
=14 x 7 :2
=7 x 7
7x7=x^2
7^2=x^2
=> x=7

Answer 2

Răspuns:

1+3+5+...+13=x²

(13-1):2 +1=7  → nr de elemente

S=[(1+13)·7]/2

S=(14·7)/2

S=98:2=>S=49

49=x²=>x=√49=>x=7