Register Now

Login

Lost Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

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

Toán Lớp 8: x^2 + 4x – y^2 + 4 3x^2 – 3xy – 5x + 5y

Toán Lớp 8: x^2 + 4x – y^2 + 4
3x^2 – 3xy – 5x + 5y

Comments ( 2 )

  1. Giải 
     -Có : x2  + 4x – y2 + 4
    = (x2 + 4x + 4) – y2
    = (x + 2)2 – y2
    = (x + 2 – y)(x + 2 + y).
    -Có : 3x^2 – 3xy – 5x + 5y
    =(3x^2 – 3xy) – (5x – 5y)
    = 3x(xy)5(xy)
    = (xy)(3x5).
    Chúc bạn thi tốt !
    Cho mình 5 sao và ctlhn nhé.
     

  2. x^2+4x-y^2+4 
    =(x^2+4x+4)-y^2
    =(x^2-2.x.2+2^2)-y^2
    =(x+2)^2-y^2
    =(x+2-y)(x+2+y)
    3x^2-3xy-5x+5y
    =(3x^2-3xy)-(5x-5y)
    =3x(x-y)-5(x-y)
    =(x-y)(3x-5)
    Ta áp dụng hằng đẳng thức:
    a^2-b^2=(a-b)(a+b
    (a+b)^2=a^2+2ab+b^2
     

Leave a reply

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

About Melanie