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

Toán Lớp 8: Bài 2. Rút gọn biểu thức sau: a)(x+y)²-(x-y)² b)2x(x+4y) +(y-4x)²+(x+y)(x-y) c) (a+b)³-(a-b)³-2b³ d)5(x+3y) -15x(x+ 3y) e) 3(x-y)-5x(y-

Tháng Chín 10, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: Bài 2. Rút gọn biểu thức sau:
a)(x+y)²-(x-y)²
b)2x(x+4y) +(y-4x)²+(x+y)(x-y)
c) (a+b)³-(a-b)³-2b³
d)5(x+3y) -15x(x+ 3y)
e) 3(x-y)-5x(y-x)
d) x²-5x+6

Comments ( 1 )

  1. tuyen98
    tuyen98
    10 Tháng Chín, 2022 at 9:31 sáng
    Reply
    a)
     (x+y)²-(x-y)²
    =(x²+2xy+y²)-(x²-2xy+y²)
    =x²+2xy+y²-x²+2xy-y²
    =4xy
    b)
    2x(x+4y) +(y-4x)²+(x+y)(x-y)
    =2x²+8xy+y²-8xy+16x²+x²-y²
    =18x²
    c)
    (a+b)³-(a-b)³-2b³
    =a³+3a²b+3ab²+b³-(a³-3a²b+3ab²-b³)-2b³
    =a³+3a²b+3ab²+b³-a³+3a²b-3ab²+b³-2b³
    =6a²b
    d)
    5(x+3y) -15x(x+ 3y)
    =(x+3y)(5-15x)
    =5(x+3y)(1-3x)
    e)
    3(x-y)-5x(y-x)
    =3(x-y)+5x(x-y)
    =(x-y)(3+5x)
    d)
    x²-5x+6
    =x²-2x-3x+6
    =x(x-2)-3(x-2)
    =(x-2)(x-3)
    @Q.Anh 

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

Thúy Mai

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