Question

Imi poate spune cineva cat fac 2^2x-6 ori 2^x+8=0?

Answer 1

2^(2x)-6*(2^x)+8=0
(2^x)^2 -6*(2^x) +8=0
2^x=t

t^2 -6t +8=0
(t-2)(t-4)=0
t-2=0, t=2, 2^x=2, x=1
t-4=0, t=4, 2^x=4, x=2

Ecuatia are doua solutii: x=1 si x=2