3. a) Ta có : 13.29 = 377
25.17 = 425
=> \(\dfrac{13}{17}< \dfrac{25}{29}\)
b) Ta có : 59.105 > 56.101
=> \(\dfrac{59}{101}>\dfrac{56}{105}\)
c) Ta có : 14.83 = 1162
20.55 = 1100
=> \(\dfrac{14}{55}>\dfrac{20}{83}\)
d) Ta có : 13.73 = 949
29.57 = 1653
=> \(\dfrac{13}{57}< \dfrac{29}{73}\)
e) Ta có : \(\dfrac{1717}{2121}=\dfrac{17}{21}\)
=> \(\dfrac{17}{21}=\dfrac{1717}{2121}\)
@Đặng Vũ Hoài Anh
a, 3x+2 - 8.3x = 81
<=> 3x.9 - 8.3x = 81
<=> 3x(9 - 8) = 81
<=> 3x = 81
<=> 3x = 34
<=> x = 4
b, (x - 1)2 = (x - 1)3
<=> (x - 1)2 - (x - 1)3 = 0
<=> (x - 1)2.[1 - (x - 1)] = 0
<=> (x - 1)2.(1 - x + 1) = 0
<=> (x - 1)2.(2 - x) = 0
<=> \(\left[{}\begin{matrix}\left(x-1\right)^2=0\\2-x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x=2\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\) (thỏa mãn)
@Kfkfj