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- alexLv 72 years agoFavourite answer
Right side , convert to log base 5 , 4/log(x+3) , all log has base 5

If x+3>1 or x > -2 , then (log(x+3))^2 ≥ 4 ---> x ≥ 5^2 - 3 = 22

If 0<x+3<1 or -3<x<-2 , then (log(x+3))^2 ≤ 4 ---> -2 ≤ log(x +3)≤ 2 ---> -3 + 1/25 ≤ x <-2

hence x ≥22 or -74/25≤ x <-2

- rotchmLv 72 years ago
Let L = log_5. Use log_b (a) = log(a)/log(b). We get:

L(x+3) = L(625)/L(x+3). But L(625) = 4 [why?]. So you have:

L(x+3) = 4/L(x+3)

L²(x+3) = 4.

Surely u can take it from there.

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