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

Toán Lớp 8: Bài 1 : Tìm x hoặc y ! a, ( 3y^2 – y + 1 ) ( y – 1 ) + y^2 ( 4 – 3y ) = 5/2 b, 2x^2 + 3 ( x – 1 ) ( x + 1) = 5x ( x + 1 ) Giúp emm nha

Toán Lớp 8: Bài 1 : Tìm x hoặc y !
a, ( 3y^2 – y + 1 ) ( y – 1 ) + y^2 ( 4 – 3y ) = 5/2
b, 2x^2 + 3 ( x – 1 ) ( x + 1) = 5x ( x + 1 )
Giúp emm nhanh voi a

Comments ( 2 )

  1. a)
    (3y^2-y+1)(y-1)+y^2(4-3y)=5/2
    <=> 3y^3-y^2+y-3y^2+y-1+4y^2-3y^3=5/2
    <=> (3y^3-3y^3)+(4y^2-y^2-3y^2)+(y+y)=5/2+1
    <=> 2y=7/2
    <=> y=7/4
    Vậy y=7/4
    b)
    2x^2+3(x-1)(x+1)=5x(x+1)
    <=> 2x^2+3(x^2-1)=5x^2+5x
    <=> 2x^2+3x^2-3-5x^2-5x=0
    <=> -5x=3
    <=> x=-3/5
    Vậy x=-3/5
     

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