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

Toán Lớp 8: c) ( x + 3 )^2 – ( x + 5 ).( x – 4 ) = 20 + 4x

Home/ Toán Lớp 8: c) ( x + 3 )^2 – ( x + 5 ).( x – 4 ) = 20 + 4x

Toán Lớp 8: c) ( x + 3 )^2 – ( x + 5 ).( x – 4 ) = 20 + 4x

Tháng Chín 20, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: c) ( x + 3 )^2 – ( x + 5 ).( x – 4 ) = 20 + 4x

Comments ( 2 )

  1. truongthanhhung
    truongthanhhung
    20 Tháng Chín, 2022 at 10:18 sáng
    Reply
    Ta có:(x+3)²-(x+5).(x-4)=20+4x
    →x²+6x+9-(x²-4x+5x-20)=20+4x
    →x²+6x+9-(x²+x-20)=20+4x
    →x²+6x+9-x²-x+20=20+4x
    →5x+39=20+4x
    →5x+39-(20+4x)=0
    →5x+39-20-4x=0
    →x+19=0
    →x=-19
    KL:Vậy:x=-19
     

  2. kimoanh34
    kimoanh34
    20 Tháng Chín, 2022 at 10:18 sáng
    Reply
    c) ( x + 3)^{2} – ( x + 5).( x – 4) = 20 + 4x
    ⇒ x^{2} + 6x + 9 – x^{2} – 4x + 5x – 20 – 4x = 20
    ⇒ 3x – 11 = 20
    ⇒ 3x = 31
    ⇒ x = 31/3
     

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

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