Se logx 25 = - 2, então log 5 x é igual a:

Your question is on Spanish but I'll try to answer it

log x 25 = - 2 = > x^-2 = 25

we know that x^-2 is the reciprocal value that is also written as (1/x) ^2, according to this

=> (1/x) ^2 = 5^2 = > 1/x = 5 = > x = 1/5

Check log (1/5) 25 = x = > (1/5) ^x = 5^2 = > 5^-x = 5^2 = > - x=2 = >

x = - 2 Good luck!