3 log (x^2 + 1) . 5 log 3 = 5 log (x+21) apabila x = ... A. 3 B. 4 C. 5 D. -5 atau 4 E. -4 atau 5 Note = letak 3 diatas log (x^2 +1) = letak 5 diatas log 3 = le

Mata Pelajaran : Matematika Peminatan
Kelas : 10
Bab : 02 - Fungsi Logaritma



[tex] {}^{3} log(x {}^{2} + 1 ) \times {}^{5} log(3) = {}^{5} log(x + 21) \\ \frac{ {}^{5} log(x {}^{2} + 1) }{ {}^{5} log(3) } \times {}^{5} log(3) = {}^{5} log(x + 21) \\ {}^{5} log(x {}^{2} + 1 ) = {}^{5} log(x + 21) \\ x {}^{2} + 1 = x + 21 \\ x {}^{2} + 1 - x - 21 = 0 \\ x {}^{2} - x - 20 = 0 \\ [/tex]

(x - 5) , (x + 4)
→ x = 5
→ x = -4

Jawaban : E