Jika f(3x+1)=(2x+5). (X-1), maka nilai f(13) adalah...

Kelas 8 Matematika
Bab Fungsi

3x + 1 = 13
3x = 13 - 1
x = 12/3
x = 4

(2x + 5) (x - 1)
= (2 . 4 + 5) (4 - 1)
= (8 + 5) . 3
= 13 . 3
= 39