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

Toán Lớp 8: $x^{3}$ + $4x^{2}$ – 7x – 10 = 0 $(x + 2)^{2}$ = 25 $x^{2}$ + 10x + 9

Toán Lớp 8: $x^{3}$ + $4x^{2}$ – 7x – 10 = 0
$(x + 2)^{2}$ = 25
$x^{2}$ + 10x + 9

Comments ( 2 )

  1. x^3 + 4x^2 – 7x – 10 = 0
    x^3 – 2x^2 + 6x^2 – 12x + 5x – 10 = 0
    x^2 ( x – 2 ) + 6x ( x – 2 ) + 5 ( x – 2 ) = 0
    ( x – 2 ) ( x^2 + 6x + 5 ) = 0
    ( x – 2 ) x ( x + 1 ) + 5 ( x + 1 ) = 0
    ( x + 1 ) ( x + 5 ) ( x – 2 ) = 0
    x + 1 = 0       | x + 5 = 0         | x – 2 = 0
    x = – 1           | x = – 5             | x = 2
    Vậy x = – 1 hoặc x = – 5 hoặc x = 2
    ( x + 2 )^2 = 25
    ⇒ ( x + 2 )^2 = 5^2
    ⇒ x + 2 = 5
    ⇒ x = 3
    x^2 + 10x + 9
    = x^2 + 9x + x + 9
    = x ( x + 9 ) + x + 9
    = ( x + 1 ) ( x + 9 )

  2. Giải đáp:
     chúc hok giỏi nha
     

    toan-lop-8-3-4-2-7-10-0-2-2-25-2-10-9

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