LOgaritma

no. 9

soal

³log² (x - 2) - ³log (x - 2) - 6 = 0

misal :

³log (x - 2) = a

a² - a - 6 = 0

(a - 3)(a + 2) = 0

a = 3 atau a = -2

a = 3

³log (x - 2) = 3

x - 2 = 3³

x = 29

a = -2

³log (x - 2) = -2

x - 2 = 3^-2

x = 2 + 1/3²

x = 2 1/9

x = 19/9

(m + n)/4

= (29 + 19/9)/4

= 280/36

no. 10

soal

2x² - x ≥ 21

berubah tanda krn basis → 0 < basis < 1

2x² - x - 21 ≥ 0

(2x - 7)(x + 3) ≥ 0

x ≤ -3 atau x ≥ 7/2

nilai x :

x ≤ -3 atau x ≥ 7/2

no. 11

log (x² - 8x) ≥ 2

x² - 8x ≥ 10²

x² - 8x - 100 ≥ 0

dg rumus abc :

x ≤ 4 - 2√29 atau x ≥ 4 + 2√29

selang nilai x :

x ≤ 4 - 2√29 atau x ≥ 4 + 2√29