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

Toán Lớp 8: phân tích đa thức thành nhân tử: 1, (3x+1)^2 – 49 2, x^2 – 4xy + 4y^2 3, (ax + by)^2 – (ax – by)^2 4, 8x^3 + 125y^3 5, x^4 + 4x^2 – 5

Toán Lớp 8: phân tích đa thức thành nhân tử:
1, (3x+1)^2 – 49
2, x^2 – 4xy + 4y^2
3, (ax + by)^2 – (ax – by)^2
4, 8x^3 + 125y^3
5, x^4 + 4x^2 – 5

Comments ( 2 )

  1. Đáp án:
     
    Giải thích các bước giải:
     

    toan-lop-8-phan-tich-da-thuc-thanh-nhan-tu-1-3-1-2-49-2-2-4y-4y-2-3-a-by-2-a-by-2-4-8-3-125y-3-5

  2. $\text {1, }$
    (3x+1)^2-49
    = (3x+1)^2-7^2
    = (3x+1-7)(3x+1+7)
    = (3x-6)(3x+8)
    $\text {2,}$
    x^2-4xy+4y^2
    = (x-2y)^2
    $\text {3,}$
    (ax+by)^2-(ax-by)^2
    = (ax+by-ax+by)(ax+by+ax-by)
    = 2by.2ax
    $\text {4,}$
    8x^3+125y^3
    = (2x+5y)(4x^2+10xy+25y^2)
    $\text {5,}$
    x^4+4x^2-5
    = [(x^2)^2+2.2x^2+4]-9
    = (x^2+2)^2-3^2
    = (x^2+5)(x^2-1)
    = (x^2+5)(x-1)(x+1)
    $\text {@lamtung2007}$

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