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

Toán Lớp 8: Bài 2. Rút gọn các biểu thức sau: a) 3×2 – 2x(5 + 1,5x) + 10 b) (2x – 3)(x + 7) – 2x(x + 5) – x c) (x + 3)(x – 3) – (x – 5)(x + 2) d)

Tháng Một 4, 2023 Toán học 2 Comments 0 views

Toán Lớp 8: Bài 2. Rút gọn các biểu thức sau:
a) 3×2 – 2x(5 + 1,5x) + 10 b) (2x – 3)(x + 7) – 2x(x + 5) – x
c) (x + 3)(x – 3) – (x – 5)(x + 2) d) (x – 1)2 – (x + 2)(x – 2)
e) (x + 2)(x2 – 2x + 4) – x(x2 + 2) f) (x + 2y)3 – 6xy(x + 2y)

Comments ( 2 )

  1. hienthucthu97
    hienthucthu97
    4 Tháng Một, 2023 at 12:32 chiều
    Reply
    a, 3x² – 2x(5 + 1,5x) + 10
    =3x² – 10x – 3x² + 10
    = 10 – 10x
    b, (2x – 3)(x + 7) – 2x(x + 5) – x
    =2x² + 14x – 3x – 21 – 2x² – 10x – x
    = -21
    c, (x + 3)(x – 3) -(x-5)(x+2)
    = x² – 9 – (x² + 2x – 5x – 10)
    = x² – 9 – x² – 2x + 5x + 10
    = 3x + 1
    d, (x – 1)² – (x + 2)(x – 2)
    = x² – 2x + 1 – x² + 4
    = 5 – 2x
    e, (x + 2)(x² – 2x + 4) – x(x² + 2)
    = (x + 2)(x – 2)² – x³ – 2x
    = (x² – 4)(x – 2) – x³ – 2x
    = x³ – 2x² – 4x + 8 – x³ – 2x
    = -2x² – 6x + 8 
    f, (x + 2y)³ – 6xy(x + 2y)
    = x³ + 6x²y + 12xy² + 8y³ – 6x²y – 12xy²
    = x³ + 8y³

  2. cattien
    cattien
    4 Tháng Một, 2023 at 12:32 chiều
    Reply

    a.3×2-2x(5+1.5x) +10=-10x+10
    B. (2x-3)(x+7)-2x(x+5)-x=-21
    C. (x+3)(x-3)-(x-5)(x+2)=-7x-19
    D. (x-1)2-(x+2)(x-2)=-x^2+2x-2
    E. (x+2)(x^2-2x+4)-x(x^2+2)=-2x+8
    F. (x+2y) 3-6xy(x+2y) =

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

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