Question

Să se rezolve ecuațiile:​

Answer 1

Răspuns:

Explicație pas cu pas:

a) log4(x) = log4(4^2),  x = 4^2 = 16

b) x -1 > 0,  x > 1

lg(x-1) = -1 = lg(1/0),  x -1 = -1/10,  x = 1- 1/10 = 9/10

Nu convine pt. ca  9/10 < 1

c) 7x +1 > 0,  x > -1/7

log9(3^3) =

    log3(3^3)/log3(3^2) = 3/2 ( am schimbat baza in 3)

log1/4(7x+1) = 3/2 =log1/4(1/4)^(3/2) = log1/4(1/8) pt.ca:

   4^(3/2) = √(4^3) = √(2^6) = 2^3 = 8

7x +1 = 1/8,  7x = 1/8 -1 ,  x = -7/8  

Nu convine pt. ca -7/8 < -1/7

etc.