a/ ( x + 3)^2 e/ ( 1 – x) (1 + x) b/ ( 2x + y)^2 f/ ( 5 – x^2)(5 + x^2) c/ (x-1/2)^3

0 bình luận về “a/ ( x + 3)^2 e/ ( 1 – x) (1 + x) b/ ( 2x + y)^2 f/ ( 5 – x^2)(5 + x^2) c/ (x-1/2)^3”

1. `a) (x + 3)^2 = x^2 + 2.x.3 + 3^2 = x^2 + 6 x + 9`

   `b)(2x + y)^2 = (2x)^2 + 2.2x.y + y^2 = 4x^2 + 4xy + y2`

   `c)(x-1/2)^3=x^2-2x.1/2+(1/2)^2=x^2-x+1/4`

   `d)(5 – 3x)^2 = 5^2 – 2.5.3x + (3x)^2 = 25 – 30x + 9x^2 `

   `e)(1 – x) (1 + x) = 1^2 – x^2 = 1 – x^2`

   `f)(5 – x^2)(5 + x^2) = 52 – (x^2)^2 = 25 – x^4`

   `g)(2x – 1)^3 = (2x)^3 – 3.(2x)^2.1 + 3.2x.1^2 – 1^3 = 8x^3 – 12x^2 + 6x – 1`

   `h)(x + 3) (x^2 – 3x + 9)= (x + 3) (x^2 – 3x + 3^2) = x^3 + 3^3 = x^3 + 27`

   `i)(2x – y)(4x^2 + 2xy + y^2) = (2x)^3 – y^3 = 8x^3 – y^3`

   Bình luận

2. Đáp án:

    

   Giải thích các bước giải:

    a) (x+3)² = x²+ 6x + 9

   b) (2x+y)² = 4x² + 4xy + y²

   c) (x-1)³ = x³- 3x² + 3x – 1

   d) ( 5- 3x)² = 25 – 30x + 9x²

   e) (1-x) (1+x) = 1-x²

   f) (5-x²)(5+x²)= 25- (x²)²

   g) (2x-1)³ = 8x³ – 12x² + 6x – 1

   h)( x + 3)(x^2 – 3x + 9)= x³+ 3³

   i/(2x – y)(4x^2 + 2xy + y^2) = 8x³- y³

   Bình luận