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

Toán Lớp 8: rút gọn biểu thức (5x+1)(2x-3)-(7x-2)(x+3)+5

Toán Lớp 8: rút gọn biểu thức (5x+1)(2x-3)-(7x-2)(x+3)+5

Comments ( 2 )

  1. $(5x+1)(2x-3)-(7x-2)(x+3)+5$
    $=10x^2-15x+2x-3-(7x^2+21x-2x-6)+5$
    $=10x^2-15x+2x-3-7x^2-21x+2x+6+5$
    $=(10x^2-7x^2)+(-15x+2x-21x+2x)+(-3+6+5)$
    $=3x^2-32x+8$

  2. (5x+1)(2x-3)-(7x-2)(x+3)+5
    =10x^2-15x+2x-3-7x^2-21x+2x+6+5
    =(10x^2-7x^2)+(-15x+2x-21x+2x)+(-3+6+5)
    =3x^2-32x+8
     

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