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

Toán Lớp 8: `a)` `(x – 3y)^2` `b)` `(4 – 3y)^3` `c)` `1 – 3x + 3x^2 – x` `d)` `(1 + x +y )^2` `e)` `(x – y + 3)^2`

Toán Lớp 8: a) (x – 3y)^2
b) (4 – 3y)^3
c) 1 – 3x + 3x^2 – x
d) (1 + x +y )^2
e) (x – y + 3)^2

Comments ( 2 )

  1. #kehuydiet
    a. (x-3y)^2
    = x^2-3.x.3y+(3y)^2
    = x^2-9xy+9y^2
    b. (4-3y)^3
    = 4^3-3.4^2.3y+3.4.(3y)^2-(3y)^3
    = 64-48y+108y^2-27y^3
    c. 1-3x+3x^2-x
    = (1-x)^3
    d. (1+x+y)^2
    = 1+x^2+y^2+2x+2y+2xy
    e. (x-y+3)^2
    = x^2+y^2+9-2xy+6x-6y

  2. Giải đáp:
    a) x^2 – 6xy + y^2
    b) 64 – 144y + 108y^2 – 27y^3
    c) (1 – x)^3
    d) 1^2 + x^2 + y^2 + 2x + 2y + 2xy
    e) x^2 + y^2 – 9 – 2xy – 6y + 6x
    Lời giải và giải thích chi tiết:
    a) (x – 3y)^2
    = x^2 – 2x.3y + y^2
    = x^2 – 6xy + y^2
    b) (4 – 3y)^3
    = 4^3 – 3.4^2.3y + 3.4.(3y)^2 – (3y)^3
    = 64 – 3.16.3y + 3.4.9y^2 – 27y^3
    = 64 – 144y + 108y^2 – 27y^3
    c) 1 – 3x + 3x^2 – x
    = 1^3 – 3.1^2.x + 3x^2.1 – x^3
    = (1 – x)^3
    d) (1 + x +y )^2
    = 1^2 + x^2 + y^2 + 2x + 2y + 2xy
    e) (x – y + 3)^2
    = x^2 + y^2 – 9 – 2xy – 6y + 6x

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