10 × (2y - 10) = (10 × 2y) - (10 × 10)
= (10 × 2)y - 100
= 20y - 100
b.(x + 5) × (5x - 1) = ...
Cara Penyelesaian:
Baca Juga: Kunci Jawaban Matematika Kelas 7 Halaman 204 205 Ayo Kita Berlatih 3.1, Bentuk Aljabar Nomor 1-6
(x+ 5) × (5x - 1) = x(5x - 1) + 5 (5x - 1)
= (x(5x) - x(1)) + (5(5x) - 5(1))
= 5(x)(x) - x + (5)(5)x - 5
= 5x² - x + 25x - 5