(2x+2y)³=? x³-1= 49-x²= (x-2)³= M.n giúp e vs ạ

2 bình luận về “(2x+2y)³=? x³-1= 49-x²= (x-2)³= M.n giúp e vs ạ”

1. +) (2x+2y)³=(2x)^3 + 3.(2x)^2.(2y) + 3.(2x).(2y)^2 + (2y)^3

   = 8x^3 + 24x^2y + 24xy^2 +8y^3

   +) x³-1=x^3-1^3=(x-1)(x^2+x+1)

   +) 49-x²=7^2-x^2=(7-x)(7+x)

   +) (x-2)³=x^3 – 3.x^2.2 + 3.x.2^2 – 2^3 = x^3 – 6x^2 + 12x – 8

   Trả lời
2. Giải đáp:

   a) (2x+2y)^3

   = [2(x+y)]^3

   = 8(x+y)^3

   = 8(x^3+3x^2y+3xy^2+y^3)

   b) x^3-1

   = x^3-1^3

   = (x-1)(x^2+x.1+1^2)

   = (x-1)(x^2+x+1)

   c) 49 – x^2

   = 7^2 – x^2

   = (7+x)(7-x)

   d) (x-2)^3

   = x^3 – 3.x^2 . 2 + 3.x.2^2 – 2^3

   = x^3 – 6x^2 + 12x – 8

   Trả lời