Chứng tỏ: (a – b – c) – (a + b – c) + (b – c – a) – (c – a – b) + 5 = –2c + 5

0 bình luận về “Chứng tỏ: (a – b – c) – (a + b – c) + (b – c – a) – (c – a – b) + 5 = –2c + 5”

1. VT = a – b – c – a – b + c + b – c – a – c + a + b + 5

        = (a -a  -a +a) + ( -b -b +b +b) + (-c +c -c -c ) + 5

        = -2c +5

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2. Ta có:

   VT = (a – b – c) – (a + b – c) + (b – c – a) – (c – a – b) + 5

   = a – b – c – a – b + c + b – c – a – c + a + b + 5

   = (a – a – a + a) – (b + b – b – b) – (c – c + c + c) + 5

   = 0 – 0 – 2c + 5

   = 0 – 2c + 5

   = -2c + 5 = VP (đpcm)

   VT: vế trái

   VP: vế phải

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