Question

Chứng minh rằng nếu (a + 2009)(b - 2010) = (a - 2009)(b + 2010) thì 2010a = 2009b.

Answer 1

Ta có: (a + 2009)(b - 2010) = (a - 2009)(b + 2010) 

=> ab - 2010a + 2009b - 2009.2010 = ab + 2010a - 2009b - 2009.2010

=> ab - 2010a + 2009b - 2009.2010 - ab - 2010a + 2009b + 2009.2010 = 0

=> -2010a + 2.2009b = 0

=> 2010a = 2.2009b

Đề sai

Answer 2

Ta có: (a + 2009)(b - 2010) = (a - 2009)(b + 2010)

=> ab - 2010a + 2009b - 2009.2010 = ab + 2010a - 2009b - 2009.2010

=> ab - 2010a + 2009b - 2009.2010 - ab - 2010a + 2009b + 2009.2010 = 0

=> -2010a + 2.2009b = 0

=> 2010a = 2.2009b Đề sai 

Answer 3

Các bạn trả lời sai rồi -2010-2010=2(-2010)