Question

Rezolvati ecuatia 2×2^x+4^x-8^x=0

Answer 1

fie 2^x=t

atunci

2t+t²-t³=0

t³-t²-2t=0

t(t²-t-2)=0

t1=0.. 2^x=0..x∈∅

t2=-1..2^x=-1...x∈∅

t3=2...2^x=2...x=1 solutie unica

verificare

4+4-8=0.......:::)))

obs ;am tinut cont ca 2^x>0, ∀x∈R