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

Toán Lớp 8: (2x+5y)mũ2 (x^2-5y)mũ3 (2x^2+3y)(3y-2x^2)

Toán Lớp 8: (2x+5y)mũ2
(x^2-5y)mũ3
(2x^2+3y)(3y-2x^2)

Comments ( 2 )

  1. Trả lời :
    (2x+5y)^2 = (2x)^2+2.2x.5y+(5y)^2 = 4x+20xy+25y
    (x^2-5y)^3 = (x^2)^3 -3.(x^2.)^2.5y +3.(x^2).(5y)^2 – (5y)^3 = x^6 -3x^4.5y +3.x^2.25.y^2 – 125.y^3
    =x^6 – 15x^4.y+75.x^2.y^2 =-125y^3
    (2x^2+3y)(3y-2x^2)= (2x^2)^2 – (3y)^2
    Học tốt

  2. (2x + 5y)^{2}
    = 4x^{2} + 20xy + 25y^{2}
    ( x^{2} – 5y)^{3}
    = x^{6} – 15x^{4}y + 75x^{2}y^{2} – 125y^{3}
    ( 2x^{2} + 3y)( 3y – 2x^{2})
    = 4x^{4} – 9y^{2}
    Bạn tham khảo!
     

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

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