Question

Aflati-l pe x din egalitatile:
a) $2 {}^{x + 3} = 128$

b) $3 {}^{2x - 1} = 243$

c) $4 {}^{2x + 3} = 64$

d) $2 {}^{2x + 1} + 2 {}^{2x + 3} + 4 {}^{x + 1} = 896$

dau coroana

Answer 1

a) 128= 2⁷ ⇒ x+3=7⇒ x=4

b) 243= 3⁵⇒ 2x-1=5⇒ 2x=6⇒ x=3

c) 64=4³ ⇒ 2x+3=3⇒2x=0⇒x=0

d) 2²ˣ⁺¹ +2²ˣ⁺³ +2²ˣ⁺² = 896

2²ˣ⁺¹ (1+2²+2)=896

2²ˣ⁺¹ = 896 :7

2²ˣ⁺¹ = 128⇒ 2x+1=7⇒ 2x=6⇒ x=3