1990.1990-1992.1998

=1990.1990-(1990+2).1998

=1990.1990-1990.1998+2.1998

=1990.(1990-1998)+2.1998

=1990.(-8)+2.(1990+8)

=1990.(-8)+2.1990+2.8

=1990.((-8)+2)+16

=1990.(-6)+16

=(-11940)+16

=-11924

\(\frac{423134.846267-423133}{846267.423133+423134}=\frac{\left(423134+1\right).846267-423133}{846267.423133+423134}\)

\(\frac{423133.846267+846267-423133}{846267.423133-423134}=\frac{423133.846267-423134}{864267.423133-423134}=1\)

\(\dfrac{423134.846267-423133}{846267.423133+423134}\)

\(=\dfrac{423134.846267-423133}{846267.\left(423134-1\right)+423134}\)

\(=\dfrac{423134.846267-423133}{846267.423134-846267+423134}\)

\(=\dfrac{423134.846267-423133}{846267.423134-423133}\)

\(=1\)

Chúc bạn học tốt!!!!

hổng hiểu đề

pạn ơi ???????

\(\frac{423134.846267-423133}{846267.423133+423134}\)

Xét tử số : 423134.846267-423133

= (423133+1).846267-423133

= 423133.846267+846267-423133

=423133.846267+ 423134

Ta có : \(\frac{423133.846267+423134}{846267.423133+423134}\)=1

= 1 100% bởi vì đó là tính nhanh

ks mình

ket qua la 1 nhe

 kết quả là = 1 

kết quả = 0

\(\frac{423134\cdot846267-423133}{846267\cdot423133+423134}=0\)

Tích nha bạn

a)\(2.18.6+3.19.4+12.63\)

\(=2.6.18+3.4.19+12.63\)

\(=12.18+12.19+12.63\)

\(=12.\left(18+19+63\right)\)

\(=12.100\)

\(=1200\)

b)\(12.19+12.34+12.20+88.27\)

\(=12.19+12.34+12.20+22.4.3.9\)

\(=12.19+12.34+12.20+4.3.22.9\)

\(=12.19+12.34+12.20+12.198\)

\(=12.\left(19+34+20+198\right)\)

\(=12.271\)

\(=3252\)

c) \(28.17+66.14\)

\(=14.2.17+66.14\)

\(=14.34+66.14\)

\(=14.\left(34+66\right)\)

\(=14.100\)

\(=1400\)

 a,2.18.6=216; 3.19.4=228;12.63= 756;216+228+756=1200                                                                                                                  b,12.19=228;12.34=408;12.20=240;88.27=2376;228+408+240+2376=3252                                                                                            c,1/1  

các bạn phải làm cách tính nhanh mà, các bạn làm tớ chẳng hiểu gì cả giảng cho tớ rõ hơn đi

a)1990.1990+1992.1988

=3960100+3960096

=7920196

b)(124.237+152):(870+235.122)

=(29388+152):(870+28670)

=29540:29540

=1

c)(423134.846267-423133):(846267.423133+423134)

=(423134.846267):(423133-423134)

=(423134.846267):0

=0