a)2x(3x+1)-(x-3)(6x+2) b)(2x-3)^2-(1+2x)(2x+1)+3(2x-3) c)(x+y-1)^2-2(x+y-1)(x+y)+(x+y)^2

0 bình luận về “a)2x(3x+1)-(x-3)(6x+2) b)(2x-3)^2-(1+2x)(2x+1)+3(2x-3) c)(x+y-1)^2-2(x+y-1)(x+y)+(x+y)^2”

1.  `a)2x(3x+1)-(x-3)(6x+2)`

   `=6x^2+2x-(6x^2+2x-18x-6)`

   `=6x^2+2x-6x^2-2x+18x+6`

   `=(6x^2-6x^2)+(2x-2x+18x)+6`

   `=18x+6`

   `b)(2x-3)^2-(1+2x)(2x+1)+3(2x-3)`

   `=4x^2-12x+9-(1+2x)^2+6x-9`

   `=4x^2-12x+9-1-4x-4x^2+6x-9`

   `=(4x^2-4x^2)+(-12x-4x+6x)+(9-1-9)`

   `=-10x-1`

   `c)(x+y-1)^2-2(x+y-1)(x+y)+(x+y)^2`

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

   `=[(x-x)+(y-y)-1]^2`

   `=(-1)^2`

   `=1`

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2. Đáp án+Giải thích các bước giải:

   `a)2x(3x+1)-(x-3)(6x+2)`

   `=6x^2+2x-6x^2+16x+16`

   `=(6x^2-6x^2)+(2x+16x)+16`

   `=18x+6`

   `b)(2x-3)^2-(1+2x)(2x+1)+3(2x-3)`

   `=4x^2-12x+9-4x^2-4x-1+6x-9`

   `=(4x^2-4x^2)-(12x+4x-6x)+(9-9-1)`

   `=-10x-1`

   `c)(x+y-1)^2-2(x+y-1)(x+y)+(x+y)^2`

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

   `=(-1)^2=1`

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