Question

Completati spatiile punctate:
A) Daca 2ˣ⁺¹=128 ,atunci ..........adica.....⇒x=?
b) Daca 3²ˣ⁺¹=243 atunci........adica.......⇒x=?
c) Daca 2ˣ +2ˣ⁺¹+ 2ˣ⁺²=448 atunci 2ˣ ₓ(....+....+...) =..............⇒x=?

Answer 1

a. Daca $2^{x+1}$=128 , atunci $2^{x} +2=128$ , adica $2^{x}=126$ ⇒x=63

b. Daca $3^{2x+1}=243$ , atunci $3^{2x} +3=243$ , adica $3^{2x+3} = 3^{5}$ ⇒2x+3=5⇒x=4

c. Daca $2^{x}+ 2^{x+1}+ 2^{x+2}=448$ , atunci $2^{x}( 1+2+4)=448$ = $2^{x}*7=448$ = $2^{x}=64$ ⇒$2^{x} = 2^{6}$ ⇒x=6