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

Toán Lớp 8: Rút gọn (3x+1)(x-7)-3(x-1)(x-5)-(18x-12)

Toán Lớp 8: Rút gọn
(3x+1)(x-7)-3(x-1)(x-5)-(18x-12)

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
     (3x + 1)(x – 7) – 3(x – 1)(x – 5) – (18x – 12)
    = 3x² – 21x + x – 7 – 3(x² – 5x – x + 5) – 18x + 12
    = 3x² – 20x – 7 – 3x² + 15x + 3x – 15 – 18x + 12
    = – 20x – 10

  2. $\displaystyle \begin{array}{{>{\displaystyle}l}} ( 3x+1)( x-7) -3( x-1)( x-5) -( 18x-12)\\ =3x^{2} -21x+x-7-3\left( x^{2} -5x-x+5\right) -18x+12\\ =3x^{2} -21x+x-7-3x^{2} +18x-15-18x+12\\ =-20x-10\\ \end{array}$
     

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