Question

因式分解2(a-b)²-18(2a-b)²？

Answer 1

=2（a²+2ab+b²）-18（4a²-4ab+b²）
=2a²+4ab+2b²-72a²+72ab-18b²
=-70a²+76ab-16b²

Answer 2

2 (a-b)^2 - 18 (2a-b)^2
= 2 (a^2 - 2ab + b^2) - 18 (4a^2 - 4ab + b^2)
= - 70 a^2 + 68 ab - 16 b^2
= - 2 ( 35 a^2 - 34 ab + 8 b^2)
= - 2 (7a - 4b) (5a - 2b)