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

Toán Lớp 8: Rút gọn biểu thức:(2x-3y)^2+(x+5)^2-2(2x-3y)(x+5).

Toán Lớp 8: Rút gọn biểu thức:(2x-3y)^2+(x+5)^2-2(2x-3y)(x+5).

Comments ( 2 )

  1. Lời giải và giải thích chi tiết:
    (2x – 3y)^2 + (x + 5)^2 – 2(2x – 3y)(x + 5)
    = (4x^2 – 12xy + 9y^2) + (x^2 + 10x + 25) – (4x – 6y)(x + 5)
    = 4x^2 – 12xy + 9y^2 + x^2 + 10x + 25 – (4x – 6y)(x + 5)
    = 5x^2 – 12xy + 9y^2 + 10x + 25 – (4x^2 – 6xy + 20x – 30y)
    = 5x^2 – 12xy + 9y^2 + 10x + 25 – 4x^2 + 6xy – 20x + 30y
    = x^2 – 6xy + 9y^2 – 10x + 30y + 25

  2. (2x-3y)^2+(x+5)^2-2(2x-3y)(x+5)
    =(4x^2-12xy+9y^2)+(x^2+10x+25)-(4x-6y)(x+5)
    =5x^2-12xy+9y^2+10x-(4x-6y)(x+5)+25
    =5x^2-4x^2-12xy+6xy+9y^2+10x-20x+30y+25
    =x^2-6xy+9y^2-10x+30y+25 

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