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

Toán Lớp 8: câu 1 (2x+3) ² câu 2 (3a-1) ² câu 3 (a+2) ³

Toán Lớp 8: câu 1 (2x+3) ²
câu 2 (3a-1) ²
câu 3 (a+2) ³

Comments ( 2 )

  1. Câu 1 :
    (2x+3)^2
    = (2x)^2 + 2(2x) . 3 + 3^2
    = 4x^2 + 12x +9
    $\\$
    Câu 2 :
    (3a-1)^2
    = (3a)^2 – 2 . (3a) . 1 +1
    = 9a^2 – 6a +1
    $\\$
    (a+2)^3
    = a^3 + 3a^2 . 2 + 3 . a . 2^2 + 2^3
    = a^3 + 6a^2 + 12a + 8
     $\\$
    Câu 4 :
    (x-4)^3
    = x^3 – 3x^2 . 4 + 3 . x . 4^2 -4^3
    = x^3 – 12x^2 + 48x – 64

  2. 1, (2x+3)^2
    =(2x)^2+2.2x.3+3^2
    =4x^2+12x+9
    2, (3a-1)^2
    =(3a)^2-2.3a+1
    =9a^2-6a+1
    3, (a+2)^3
    =a^3+3.a^2.2+3a.2^2+2^3
    =a^3+6a^2+12a+8
    4, (x-4)^3
    =x^3-3.x^2.4+3.x.4^2-4^3
    =x^3-12x^2+48x-64

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