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

Toán Lớp 8: AI NHANH NHẤT ĐƯỢC 5 SAO , CẢM ƠN HAY NHẤT NHA a ) 3x . ( x – 2 ) – x . ( 1 + 3x ) = 14 b ) ( 3x + 1 ) + ( 5x -2 )^2 = 34 . ( x + 2 ) .

Toán Lớp 8: AI NHANH NHẤT ĐƯỢC 5 SAO , CẢM ƠN HAY NHẤT NHA
a ) 3x . ( x – 2 ) – x . ( 1 + 3x ) = 14
b ) ( 3x + 1 ) + ( 5x -2 )^2 = 34 . ( x + 2 ) . ( x – 2 )
c) x^3 + 3x^2 + 3x + 1 = 125

Comments ( 2 )

  1. ~ Bạn tham khảo ~
    a, 3x( x – 2 ) – x( 1 + 3x ) = 14
    <=> 3x^2 – 6x – x – 3x^2 = 14
    <=> -7x = 14
    <=> x=-2
    Vậy x=-2
    b, (3x+1)^2 + (5x-2)^2 = 34(x+2)(x-2) (Sửa đề tí nhé)
    <=> 9x^2 + 6x + 1 + 25x^2 – 20x + 4 – 34(x^2 – 4) = 0
    <=> 9x^2 + 6x + 1 + 25x^2 – 20x + 4 – 34x^2 + 136 = 0
    <=> -14x + 141 = 0
    <=> -14x = -141
    <=> x= 141/14
    Vậy x=141/14
    c, x^3 + 3x^2 + 3x + 1 = 125
    <=> x^3 + 3*x^2* 1 + 3* x * 1^2 + 1^3 = 5^3
    <=> (x+1)^3 = 5^3
    <=> x+1 = 5
    <=> x=4
    Vậy x=4

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

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