Cho a – b = 10. Hãy tính A = (2a – 3b)² + 2(2a – 3b)(3a – 2b) + (2b – 3a)².

A = (2a – 3b)² + 2(2a – 3b)(3a – 2b) + (2b – 3a)²

A = (2a – 3b)² + 2(2a – 3b)(3a – 2b) + (3a – 2b)²

A = [(2a – 3b) + (3a – 2b)]²

A = (5a – 5b)²

A = 5²(a – b)²

A = 25 . 10²

A = 2500.