Question

lg (1-x)-lg (7-x)=-1​

Answer 1

Răspuns:

1/3

Explicație pas cu pas:

1-x>0, x<1

7-x>0, x<7 si intersectand conditiile de existenta, avem conditia impusa x<1.

lg[(1-x)/(7-x)] = -1

(1-x)/(7-x) = 10^(-1)

(1-x)/(7-x) = 1/10

10(1-x) = 7-x

10 -10x = 7-x

3 = 9x

x = 3/9 = 1/3.