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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Toán lớp 8 . Rút gọn các biểu thức sau:(x+2)^3+(x-1)^3

Toán Lớp 8: Toán lớp 8 . Rút gọn các biểu thức sau:(x+2)^3+(x-1)^3

Comments ( 2 )

  1. (x+2)^3 + (x-1)^3
    = x^3 + 6x^2 + 12x + 8 + x^3 – 3x^2 + 3x -1
    =(x^3 +x^3 ) + (6x^2 – 3x^2 ) + (12x + 3x) + (8-1)
    = 2x^3 + 3x^2 + 15x + 7

  2. (x+2)^3+(x-1)^3 $\\$
    =x^3+3.x^2. 2+3.x. 2^2+2^3+x^3-3.x^2 .1+3.x.1^2-1^3 $\\$
    =x^3+6x^2+12x+8+x^3-3x^2+3x-1 $\\$ 
    =(x^3+x^3)+(6x^2-3x^2)+(12x+3x)+(8-1) $\\$
    =2x^3+3x^2+15x+7 $\\$
    =2x^3+3x^2+15x+7 $\\$

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222-9+11+12:2*14+14 = ? ( )

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