“See?” Dani smiled. “We didn’t need page 55. We just needed to think like page 55.”
Then they recalled a word problem: Sebuah amoeba membelah diri menjadi dua setiap 20 menit. Jika mula-mula ada 4 amoeba, berapa banyak setelah 2 jam? (“An amoeba splits into two every 20 minutes. Initially there are 4 amoeba, how many after 2 hours?”)
( 4 \times 64 = 256 ) amoeba.
Here’s a story built around an exponents problem:
Dani grinned. “So we’ll solve it like we solve equations — piece by piece.” matematika kelas 9 halaman 55
Dani scribbled a memory-fragment: ( \frac{3^7}{3^4} ). “Subtract exponents,” she said. ( 3^{7-4} = 3^3 = 27 ).
“It’s torn out!” Rina groaned.
“Two hours = 120 minutes,” Rina calculated. “120 ÷ 20 = 6 divisions.”
“But each amoeba doubles each time,” Dani added. “Start: ( 4 ) → after 1 split: ( 4 \times 2 = 8 ), after 2 splits: ( 8 \times 2 = 16 ), etc. That’s ( 4 \times 2^6 ).” “See