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

Toán Lớp 8: rút gọn biểu thức a) 3x mũ 2 ( x mũ 2 – 5x ) b) ( x + 1 ) tất cả mũ 2 – ( x – 2 )( x + 2 ) – 2x c) ( 6x + 1 ) tất cả mũ 2 + 2( 1 + 6x )

Toán Lớp 8: rút gọn biểu thức
a) 3x mũ 2 ( x mũ 2 – 5x )
b) ( x + 1 ) tất cả mũ 2 – ( x – 2 )( x + 2 ) – 2x
c) ( 6x + 1 ) tất cả mũ 2 + 2( 1 + 6x )( 6x – 1 ) + ( 6x – 1 ) tất cả mũ 2
hepl

Comments ( 2 )

  1. a) 3x^ 2 ( x^2 – 5x )=3x^4-15x^3
    b) ( x + 1 )^ 2 – ( x – 2 )( x + 2 ) – 2x
    =(x^2+2x+1)-(x^2-4)-2x
    =x^2+2x+1-x^2+4-2x
    =5
    c) ( 6x + 1 ) ^ 2 + 2( 1 + 6x )( 6x – 1 ) + ( 6x – 1 ) ^2
    =[(6x+1)+(6x-1)]^2
    =(6x+1+6x-1)^2
    =(12x)^2
    =144x^2

  2. a.
    3x²(x²-5x)
    =3x³(x-5)
    =3x⁴-15
    =3(x⁴-5)

    b.
    (x+1)²-(x-2)(x+2)-2x
    =x²+2x+1-x²-4-2x
    =-3

    c.
    (6x+1)²+2(1+6x)(6x-1)+(6x-1)²
    =(6x+1+6x-1)²
    =(12x)²
    =144x²

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

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