Bài 1:

a) \(3x^2-9x=3x\left(x-3\right)\)

b) \(x^2-4x+4=\left(x-2\right)^2\)

c) \(x^2+6x+9-y^2=\left(x+3\right)^2-y^2=\left(x-y+3\right)\left(x+y+3\right)\)

Bài 2: 

a) \(101^2-1=\left(101-1\right)\left(101+1\right)=102.100=10200\)

b) \(67^2+66.67+33^2=67^2+2.33.67+33^2\)

\(=\left(67+33\right)^2=100^2=10000\)

Bài 3:

\(x\left(x-3\right)+2\left(x+3\right)=0\)

\(\Leftrightarrow\left(x-3\right)\left(x+2\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-3=0\\x+2=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=3\\x=-2\end{cases}}\)

Vậy \(x=-2\)hoặc \(x=3\)

B1:

a) \(3x^2-9x=3x.\left(x-3\right)\)

b) \(x^2-4x+4=\left(x-2\right)^2\)

c) \(x^2+6x+9-y^2=\left(x+3\right)^2-y^2=\left(x+3+y\right).\left(x+3-y\right)\)

B2:

a) \(101^2-1=\left(101+1\right).\left(101-1\right)=102.100=10200\)

b) \(67^2+66.67+33^2=67^2+2.33.67+33^2=\left(67+33\right)^2=100^2=10000\)

B3:

\(x\left(x-3\right)+2\left(x-3\right)=0\)

\(\left(x-3\right).\left(x+2\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-3=0\\x+2=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=3\\x=-2\end{cases}}\)

BT1

   a, 3x² - 9x = 3x( x - 3 )

   b,  x² - 4x + 4 = ( x - 2 )²

   c,    x² + 6x + 9 - y² = ( x² + 6x + 9 ) - y²

                                   = ( x + 3 )² -y²

                                   =  ( x + 3 - y ) ( x + 3 + y )

BT2                           

a, 101² - 1 = ( 101 - 1 ) ( 101 + 1 ) = 100 . 102 = 10200

b,   67² + 66 . 67 + 33² = 67² + 2 . 67 . 33 + 33² 

                                      = ( 67 + 33 )² = 100² = 10000

BT3  

     x ( x - 3 ) + 2 ( x - 3 ) = 0

<=> ( x + 2 )( x - 3 ) = 0

<=>  x + 2 = 0         <=>  x = -2

        x - 3   = 0                 x = 3

         vậy ................

= 167 x 67 + 167 x 30 + 161 x 1 + 167 x 2 

= 167 x (67 +30 +1 + 2 )

=167 X 100

= 16 700

\(=\left(-67\right).\left(-33\right)-67.77+\left(-67\right).33-77.33\)

\(=\left[\left(-67\right).\left(-33\right)+\left(-67\right).33\right]-66.77-77.33\)

\(=-77\left(66+33\right)=-77.99=-7623\)

(67/111+2/33-15/117) . (1/3-1/4-1/12)

= (67/111+2/33-15/117) .  0

=          2836/5291         .  0

=             0

\(\left(100+67\right).67+\left(200-33\right).33\)

\(=167.67+167.33\)

\(=167.\left(67+33\right)=167.100=16700\)

ĐỀ BẠN TỰ GHI À NHA

=167x67+167x33

=167x(67+33)

=167x100

=16700

(100 + 67)  x  67 + (200 – 33)  x 33

=167x67+167x33

=167x(67+33)

=167x100

=16700

67 +135 + 33 = (67 + 33) +135 = 100 +135 - 235.

(67+ 95) + 33 = (67+ 33) + 95 = 100 + 95 = 195