Jawab:
5. [D.]  (I), (II) dan (III)
6. [B.]  a = ⁵/₂

Penjelasan :
[NOMOR 5]
Diketahui fungsi
f(x) = ⁶log (2x+4)

CHECK!
(I) Memotong sumbu x
jika f(x) = 0
0 = ⁶log (2x+4)
6⁰ = 2x+4
1 = 2x+4
2x = 1-4
2x = -3
x = -³/₂
Betul bahwa fungsi
memotong sumbu x di
titik (-³/₂, 0)

(II) Memotong sumbu y
jika x = 0
f(0) = ⁶log (2(0)+4)
f(0) = ⁶log (0+4)
f(0) = ⁶log 4
f(0) = ⁶log 2²
f(0) = 2 (⁶log 2)
f(0) = 2 (ln2)/(ln6)
f(0) = 2 (ln2)/(ln(3·2))
f(0) = 2 (ln2)/(ln3 + ln2)
Betul, bahwa fungsi
memotong sumbu y di
titik (0, 2 (ln2)/(ln3 + ln2))

(III) Monoton naik
f(x) = ⁿlog x, jika naik n > 1
f(x) = ⁶log (2x+4), n = 6, maka
Betul, jika fungsi monoton naik
bukan monoton turun.

Jawaban: [D.]  (I), (II) dan (III)

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[NOMOR 6]
Diketahui f(x) = ³log(4x-1)
melalui titik (a, 2)
a = absis = x, maka
f(a) = ³log(4a-1)
dan f(a) = 2, maka
2 = ³log(4a-1)
3² = 4a-1
9 = 4a-1
4a = 9+1
4a = 10
2a = 5
a = ⁵/₂
Jawaban: [B.]  a = ⁵/₂

(Xcvi)