Question

Rezolvati in R ecuatia (4 la puterea x) + (2 la puterea x+1) - 24=0 ?

Answer 1

4^x+2^(x+1)-24=0
2^2x+2^x·2-24=0
notam 2^x=a
a²+2a-24=0
Δ=4+4·24=100
a₁=(-2+10)/2=8/2=4
a₂=(-2-10)/2=-12/2=-6
cazul 1
daca a=4 rezulta 2^x=4
2^x=2²
x=2

cazul 2
daca a=-6
2^x=-6    nu are sens