tìm `x` a, `( x-2)(x^2 +2x +4) – X(x^2 – x) = (x+1)^2 +2`

2 bình luận về “tìm `x` a, `( x-2)(x^2 +2x +4) – X(x^2 – x) = (x+1)^2 +2`”

1. a, (x-2)(x^2+2x+4) – x(x^2 – x ) = ( x + 1 )^2 + 2

   =>  x^3 – 2^3  –  x^3 + x^2 = x^2 + 2x + 1 + 2  

   => x^3 – 8 – x^3 + x^2 – x^2 – 2x – 1 – 2 = 0

   => -2x – 11 = 0

   => -2x = 11

   => x = -11/2

   Vậy x = -11/2

    

   Trả lời
2. (x-2)(x^2 +2x+4)-x(x^2 -x)=(x+1)^2 +2

   <=>(x^3 -2^3)-(x^3 -x^2)=(x^2 +2x+1) +2

   <=>x^3 -8-x^3 +x^2=x^2 +2x+1 +2

   <=>x^2-8=x^2 +2x+3

   <=>x^2 +2x+3-x^2 +8=0

   <=>2x+11=0

   <=>2x=-11

   <=>x=-11/2

   Vậy x=-11/2

   Trả lời