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

Toán Lớp 8: Rút gọn biểu thức a, C = $(a – c + b) ^{2}$ b, D = $(x + 1 – 2y)^{2}$

Toán Lớp 8: Rút gọn biểu thức
a, C = $(a – c + b) ^{2}$
b, D = $(x + 1 – 2y)^{2}$

Comments ( 2 )

  1. a)C=(a-c+b)^2
    =(a-c+b)(a-c+b)
    =a^2-ac+ab-ac+c^2-bc+ab-bc+b^2
    =a^2+b^2+c^2+(ab+ab)+(-ac-ac)+(-bc-bc)
    =a^2+b^2+c^3+2ab-2ac-2bc
    b)D=(x+1-2y)^2
    =(x+1-2y)(x+1-2y)
    =x^2+x-2xy+x+1-2y-2xy-2y+4y^2
    =x^2+1+4y^2+(x+x)+(-2xy-2xy)+(-2y-2y)
    =x^2+1+4y^2+2x-4xy-4y
    $\text{@ThanhTruc2008}$

  2. \text{a)}
    C = (a-c+b)^2
    -> C = (a-c)^2 + 2(a-c)b + b^2
    -> C = a^2 – 2ac + c^2 + 2ab – 2cb + b^2
    $\\$
    \text{b)}
    D = (x+1-2y)^2
    -> D = (x+1)^2 – 2(x+1)2y + 4y^2
    -> D = x^2 + 2x + 1 – 4xy – 4y + 4y^2

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