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

Toán Lớp 8: Rút gon biểu thức sau (x+2).(x-2)-(x-3).(x+1)

Toán Lớp 8: Rút gon biểu thức sau (x+2).(x-2)-(x-3).(x+1)

Comments ( 2 )

  1. (x+2).(x-2)-(x-3).(x+1)
    =(x^2-4)-(x^2+x-3x-3)
    =x^2-4-(x^2-2x-3)
    =x^2-4-x^2+2x+3
    =2x-1
    mk gửi nha~
    $#chúc tus học tốt!!$
     

  2. (x+2)(x-2)-(x-3)(x+1)
    =(x^2-4)-(x^2+x-3x-3)
    =x^2-4-(x^2-2x-3)
    =x^2-4-x^2+2x+3
    =2x-1
    Áp dụng hằng đẳng thức:
    A^2-B^2=(A+B)(A-B)

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