-3log5x = -6 would equal x = 25.
First, use the Power Rule: (log b x \(^{c}\) = c log b x). Your problem should look like -log5 x³ = -6.
Second, multiply both sides by -1. Your problem should look like log5 x³ = 6. We removed the negative signs.
Third, use the Definition of Common Logarithms. ( b\(^{a}\)= x if and only if logb(x) = a). Your problem should look like x³ = 5\(^{6}\).
Fourth, simplify 5\(^{6}\) to 15625. Your problem should look like x³ = 15625.
Fifth, take the cube root of both sides. Your problem should look like x = 3√15625.
Sixth, calculate your problem to get x = 25 which is the answer.