21.74+21.27-21
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Rút gọn tử số và mẫu số, ta được:
1.1+1.1+1.1/3.3+3.3+3.3
=1.3/9.3
Rút gọn 3 trên tử với 3 dưới mẫu
Vậy A=1/9
Tick nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
A = \(\frac{7.9+2.7.3.9-3.7.4.9}{3.7.3.9+2.3.7.9.9+7.9.4.3.9}\)
= \(\frac{7.9.\left(1+6-12\right)}{3.7.9.\left(3+18+36\right)}=\frac{-5}{3.57}=\frac{-5}{171}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
B=7.9+7.2.27+3.7.36/7.3.27+7.6.81+7.9.81
B=7(9+2.27+3.36)/7(3.27+6.81+9.81)
B=9+2.27+3.36/3.27+6.81+9.81
B=9(1+2.3+12)/9(9+9.6+81)
B=1+2.3+12/9+9.6+81
B=19/144
![](https://rs.olm.vn/images/avt/0.png?1311)
A = \(\dfrac{7.9+14.27+21.36}{21.27+42.81+63.108}\)
= \(\dfrac{7.9+7.2.9.3+7.3.9.4}{21.27+21.2.27.3+21.3.27.4}\)
= \(\dfrac{\left(7.9\right)\left(2.3+3.4\right)}{\left(21.27\right)\left(2.3+.3.4\right)}\)
= \(\dfrac{1}{9}\)
@Nguyễn Ngọc Gia Hân
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
ta có: \(M=\frac{7.9+14.27+21.36}{21.27+42.81+63.108}\)
\(M=\frac{7.9+7.2.9.3+7.3.9.4}{21.27+21.227.3+21.3.27.4}\)
\(M=\frac{7.9.\left(1+2.3+3.4\right)}{21.27.\left(1+2.3+3.4\right)}\)
\(M=\frac{7.9}{3.7.3.9}\)
\(M=\frac{1}{3^2}\)
\(M=\frac{1}{9}\)
và \(N=\frac{37}{333}=\frac{37}{37.9}=\frac{1}{9}\)
\(N=\frac{1}{9}\)
\(\Rightarrow M=N\left(=\frac{1}{9}\right)\)
M= \(\frac{7.9+14.27+21.36}{21.27+42.81+63.108}\).
M= \(\frac{7.9+14.27+21.36}{7.3.9.3+14.3.27.3+21.3+36.3}\).
M= \(\frac{7.9+14.27+21.36}{7.9.9+14.27.9+21.36.9}\).
M= \(\frac{7.9+14.27+21.36}{9\left(7.9+14.27+21.36\right)}\).
M= \(\frac{1}{9}\).
Ta có: N= \(\frac{37}{333}\)= \(\frac{1}{9}\).
Vì \(\frac{1}{9}\)= \(\frac{1}{9}\) nên M= N.
Vậy M= N.
21.74 + 21.27 - 21
= 21.(74+21-1)
= 21. 94
= 1974