Question

Repede ajutooor, va rog

Answer 1

9^x-10*3^(x-1)+1=0
notam 3^x=a
9^x=(3^x)²=a²
10*3^(x-1)=10*3^x*1/3=10a/3
a²-10a/3+1=0
3a²-10a+3=0
3a²-9a-a+3=0
3a(a-3)-(a-3)=0
(a-3)(3a-1)=0
a-3=0   a=3
3a-1=0   a=1/3

3^x=a
3^x=3     deci x=1

3^x=1/3    
3^x=3⁻¹   deci x=-1