Soal Persamaan Kuadrat mix. Logaritma. Berapa banyak solusi yang memenuhi persamaan tersebut???

3x^(log x^2) - 28x^(log x) - 20 = 0
3x^(2 log x) - 28x^(log x) - 20 = 0
3x^(log x).2 - 28x^(log x) - 20 = 0
Misal x^(log x) = a
3a^2 - 28a - 20 = 0
(3a + 2)(a - 10) = 0
a = -2/3 atau a = 10

a = -2/3
x^(log x) = -2/3 => tidak ada nilai x yang memenuhi

a = 10
x^(log x) = 10
log x^(log x) = log 10
log x . log x = 1
(log x)^2 = 1
log x = ± 1
log x = 1 => log x = log 10 => x = 10
log x = -1 => log x = log 10^-1 => x = 1/10

Jadi ada 2 solusi yaitu 10 dan 1/10