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

Toán Lớp 8: Khai triển: a,(1+3x)^2 b, (x+3)^2 c, (2x-y)^3

Toán Lớp 8: Khai triển:
a,(1+3x)^2
b, (x+3)^2
c, (2x-y)^3

Comments ( 2 )

  1. $a,$ $\left(1+3x\right)^2$
    $=1^2+2\cdot \:1\cdot \:3x+\left(3x\right)^2$
    $=1+6x+9x^2$
    $b,$ $\left(x+3\right)^2$
    $=x^2+2x\cdot \:3+3^2$
    $=x^2+6x+9$
    $c,$ $\left(2x-y\right)^3$
    $=\left(2x\right)^3-3\left(2x\right)^2y+3\cdot \:2xy^2-y^3$
    $=8x^3-12x^2y+6xy^2-y^3$
     

  2. a) 
    (1+3x)^2=1+6x+9x^2
    to Áp dụng : (a+b)^2=a^2+2ab+b^2
    b)
    (x+3)^2=x^2+6x+9
    to Áp dụng : (a+b)^2=a^2+2ab+b^2
    c)
    (2x-y)^3=8x^3-12x^2 y+6xy^2-y^3
    to Áp dụng : (a-b)^3=a^3-3a^2b+3ab^2-b^3
     

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

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