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

Toán Lớp 8: a) `(x + 2y)^2` b) `(x – 3y)(x + 3y)` c) `(5 – x)^2` d) (x – 1)3 e) (3 – y)2 f) `(2x + 3y)^3` g) `(5x – y)^2` h) `(x + 4)( x2 – 4x

Toán Lớp 8: a) (x + 2y)^2
b) (x – 3y)(x + 3y)
c) (5 – x)^2
d) (x – 1)3 e) (3 – y)2
f) (2x + 3y)^3
g) (5x – y)^2
h) (x + 4)( x2 – 4x + 16)
i) (x – 3y)(x2 + 3xy + 9y2)
j) (y – 3)(y + 3)
k) (m + n)(m^2 – mn + n^2)
l) (2 – a)(4 + 2a + a^2)

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
     a) (x+2y)² =x²+2.x.2y+(2y)²
                      = x²+4xy+4y²
    b) (x-3y).(x+3y) = x²-(3y)²
                              = x²-9y²
    c) (5-x)² = 5²-2.5.x+x²
                  = 25-10x+x²
    d) (x-1)³ = x³-3.x².1+3.x.1²-1³
                  = x³-3x²+3x-1
    e) (3-y)² = 3²-2.3.y+y²
                  = 9-6y+y²
    f) (2x+3y)³ = (2x)³+3.(2x)².3y+3.2x.(3y)²+(3y)³
                      = 8x³+36x²y+54xy²+27y³
    g) (5x-y)² = (5x)²-2.5x.y+y²
                    = 25x²-10xy+y²
    h) (x+4).(x²-4x+16) = x³+4³
                                    =x³+64
    i) (x-3y).(x²+3xy+9y²) = x³-(3y)² 
                                       = x³-9y²
    j) (y-3).(y+3) = y²-3²
                         = y²-9
    k) (m+n).(m²-mn+n³) = m³+n³
    l) (2-a).(4+2a+a²) = 2³-a³
                                 = 8-a³
    *Áp dụng HĐT số 1,2,3,4,5,6,7:
    (A+B)² =A²+2AB+B²
    (A-B)² =A²-2AB+B²
    A²-B²=(A+B).(A-B)
    (A+B)³=A³+3A²B+3AB²+B³
    (A-B)³=A³-3A²B+3AB²-B³
    A³+B³ =(A+B).(A²-AB+B²)
    A³-B³ =(A-B).(A²+AB+B²)
                                   CHÚC BẠN HC TỐT!!!
    @Applesff

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

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