a,(a+b+c)^2+(a+b-c)^2 b,(a+b)^3-3(a+b)^2b+3(a+b)b^2-b^3 c,(a^2-b^2)(a^2+ab+b^2)(a^2-ab+b^2)

0 bình luận về “a,(a+b+c)^2+(a+b-c)^2 b,(a+b)^3-3(a+b)^2b+3(a+b)b^2-b^3 c,(a^2-b^2)(a^2+ab+b^2)(a^2-ab+b^2)”

1. Đáp án:

    

   Giải thích các bước giải:

    a,(a+b+c)²+(a+b-c)²

   =a²+b²+c²+2ab+2bc+2ac+a²+b²+c²-2ac-2bc+2ab

   =2c²+2b²+4ab+2a²

   =2c²+2(a+b)²

   b, (a+b)³-3(a+b)²b+3(a+b)·b²-b³

   =(a+b-b)³=a³

   c, (a²-b²)(a²+ab+b²)(a²-ab+b²)

   =[(a-b)(a²+ab+b²)]·[(a+b)(a²-ab+b²)]

   =(a³-b³)(a³+b³)

   =$a^{6}$ -$b^{6}$ 

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2. `#DyHungg`

   `a) (a+b+c)^2+(a+b-c)^2`

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

   `=a²+c²+b²+2ab+2bc+2ac+a²+b²+c²+2ab-2ac-2bc`
   `=2a²+2b²+2c²+4ab`

   …………………..

   `b) (a+b)³-3(a+b)².b+3(a+b)b²-b³`

   `=a³+3a²b+3ab²+b³-3b(a²+2ab+b²)+b²(3a+3b)-b³`

   `=a³+3a²b+3ab²+b³-3a²b-6ab²-3b³+3ab²+3b³-b³`

   `=a³`

   ………….

   `c) (a²-b²)(a²+ab+b²)(a²-ab+b²)`

   `=(a^4+a³b-ab³-b^4)(a²-ab+b²)`

   `=a^6-a^5b+a^4b^2+a^5b-a^4b^2+a^3b^3-a³b³+a²b^4-ab^5-a^2b^4+ab^5-b^6`

   `=a^6-b^6`

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