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\(\frac{1995.1994-1}{1993.1995+1994}=\frac{1995\left(1993+1\right)-1}{1995.1993+1994}\)
\(=\frac{1995.1993+1995.1-1}{1995.1993+1994}=\frac{1995.1993+1994}{1995.1993+1994}\)
=1
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\dfrac{1995\times1994-1}{1993\times1995+1994}\)
\(A=\dfrac{1995\times\left(1993+1\right)-1}{1993\times1995+1994}\)
\(A=\dfrac{1995\times1993+1995-1}{1995\times1993+1994}\)
\(A=\dfrac{1995\times1993+1994}{1995\times1993+1994}\)
\(A=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
=1995*1994-1/(1994-1)*1995+1994
=1995*1994-1/1994*1995-1995+1994
=1995*1994-1/1994*1995-1
=1
![](https://rs.olm.vn/images/avt/0.png?1311)
\(B=\)\(\frac{3+33+333+3333+33333}{4+44+444+4444+44444}\)
\(B=\frac{3.1+3.11+3.111+3.1111+3.11111}{4.1+4.11+4.111+4.1111+4.11111}\)
\(B=\frac{3.\left(1+11+111+1111+11111\right)}{4.\left(1+11+111+1111+11111\right)}\)
\(B=\frac{3}{4}\)
\(A=\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}+\frac{1}{96}+\frac{1}{192}\)
\(A.2=\left(\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}+\frac{1}{96}+\frac{1}{192}\right).2\)
\(A.2=\frac{2}{3}+\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}+\frac{1}{96}\)
=>\(A.2-A=\left(\frac{2}{3}+\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}+\frac{1}{96}\right)-\left(\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}+\frac{1}{96}+\frac{1}{192}\right)\)
\(A=\frac{2}{3}-\frac{1}{192}\)
\(A=\frac{127}{192}\)
\(\frac{1995}{1997}.\frac{1990}{1993}.\frac{1997}{1994}.\frac{1993}{1995}.\frac{997}{995}\)
Đặt \(C=\frac{1995}{1997}.\frac{1990}{1993}.\frac{1997}{1994}.\frac{1993}{1995}.\frac{997}{995}\)
\(C=\frac{1995.1990.1997.1993.997}{1997.1993.1994.1995.995}\)
\(C=\frac{1990.997}{1994.995}\)
\(C=\frac{995.2+997}{997.2+995}=1\)
\(B=\frac{3+33+333+3333+ 33333}{4+44+444+4444+44444}\)
\(\Rightarrow B=\frac{3\left(1+11+111+1111+11111\right)}{4\left(1+11+111+1111+11111\right)}=\frac{3}{4}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1995 x 1996 - 1997 / 1995 x 1994 +1993 = 3982017,001
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
1995 x 1993 -18 / 1975 + 1993 x 1994
=(1995x1993)-18):(1975+(1993x1994)
=(3976035-18):(1975+3974042)
=3976017:3976017
=1
Lưu ý:dấu'':''là dấu chia
Thế đấy,chúc bạn học tốt
\(\frac{1995\cdot1994-1}{1993\cdot1995+1994}=\frac{1995\cdot\left(1993+1\right)-1}{1993\cdot1995+1994}=\frac{1995\cdot1993+1995-1}{1993\cdot1995+1994}=\frac{1995\cdot1993+1994}{1995\cdot1993+1994}=1\)