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

Toán Lớp 8: cần gấp ạ!!! 1) x^2 – y^2 + 5y – 5x 2) x^3 + 9x^2 – 4x – 36 3) 5x(x – 2y) + 6y(2y – x) 4) 3x(x – y) – 4y(x –

Tháng Chín 30, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: cần gấp ạ!!!
1) x^2 – y^2 + 5y – 5x 2) x^3 + 9x^2 – 4x – 36 3) 5x(x – 2y) + 6y(2y – x)
4) 3x(x – y) – 4y(x – y) 5) x^2 – 2x – y^2 + 1 6) y^2 – 9x^2
7) x^2 + x + 3(x + 1) 8) 3x^2 + 6xy + 3y^2 – 3z^2 9) 9z^2 – x^2 + 2xy – y^2

Comments ( 2 )

  1. phuongthaongoc
    phuongthaongoc
    30 Tháng Chín, 2022 at 10:01 chiều
    Reply
    Giải đáp+Lời giải và giải thích chi tiết:
    $\text{#LinhSad}$

    toan-lop-8-can-gap-a-1-2-y-2-5y-5-2-3-9-2-4-36-3-5-2y-6y-2y-4-3-y-4y

  2. tuyen98
    tuyen98
    30 Tháng Chín, 2022 at 10:00 chiều
    Reply
    1) x^2 – y^2 + 5y – 5x
       = (x^2-y^2) -(5x-5y)
       = (x+y)(x-y)-5(x-y)
        = (x+y-5)(x-y)
    2) x^3 + 9x^2 – 4x – 36
       =(x^3+9x^2)-(4x+36)
       =x^2(x+9) – 4(x+9)
       = (x^2-4)(x+9)
       = (x+2)(x-2)(x+9)
    3) 5x(x – 2y) + 6y(2y – x)
       = 5x(x-2y)-6y(x-2y)
       = (5x-6y)(x-2y)
    4) 3x(x – y) – 4y(x – y)
        = (x-y)(3x-4y)
    5) x^2 – 2x – y^2 + 1
      = (x^2-2x+1) – y^2
      = (x-1)^2 – y^2
      = (x-1-y)(x-1+y)
    6) y^2 – 9x^2
       = (y-3x)(y+3x)
    7) x^2 + x + 3(x + 1)
      =(x^2+x) + 3(x+1)
      = x(x+1) + 3(x+1)
      = (x+3)(x+1)
    8) 3x^2 + 6xy + 3y^2 – 3z^2
      =3(x^2 + 2xy + y^2 – z^2)
      =3[(x^2+2xy+y^2)-z^2]
      = 3[(x+y)^2 – z^2]
      = 3(x+y-z)(x+y+z)
    9) 9z^2 – x^2 + 2xy – y^2
       = 9z^2 -(x^2 + 2xy – y^2)
       = 9z^2-(x-y)^2
       = (3z+x-y)(3z-x+y)

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

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