tìm x biết: (x+1)(x+2)-(x-3)(x+4)=6

2 bình luận về “tìm x biết: (x+1)(x+2)-(x-3)(x+4)=6”

1. (x+1)(x+2) – (x-3)(x+4)= 6

   <=> (x^2 + 2x + x + 2) – (x^2 + 4x – 3x – 12) =6

   <=> (x^2 + 3x +2) – (x^2 + x -12) = 6

   <=> x^2 + 3x + 2 – x^2 – x + 12 = 6

   <=> (x^2 – x^2) + (3x -x) + (2+12) = 6

   <=> 2x + 14 = 6

   <=> 2x = 6 – 14

   <=> 2x = -8

   <=> x = -8 : 2

   <=> x = -4

   Vậy x=-4

   #HPHG 

    

   Trả lời
2. ( x + 1 ) ( x + 2 ) – ( x – 3 ) ( x + 4 ) = 6

   ⇔ x^2 + 2x + x + 2 – ( x^2 + 4x – 3x – 12 ) = 6

   ⇔ x^2 + 3x + 2 – x^2 – 4x + 3x + 12 – 6 = 0

   ⇔ 2x + 8 = 0

   ⇔ 2x = -8

   ⇔ x = -4

   Vậy x = -4

    

   Trả lời