vo huyen thao

1999 x 7 + 1999 +1999 x 2

= 1999 x 7 + 1999 x 1 + 1999 x 2

= 1999 x ( 7 + 1 + 2 )

= 1999 x      10            = 19990

=1999.(7+1+2)

=1999.10

=19990

1999 x 7 + 1999 + 1999 x 2

= 1999 x ( 7 + 1 + 2 )

= 1999 x 10

= 19990

giai cho tao nhanh ko con bao

Sửa lại :

\(=\frac{1999.2000+1999-1}{1998+1999.2000}.\frac{7}{5}=\frac{1999.2000+1998}{1998+1999.2000}.\frac{7}{5}=1.\frac{7}{5}=\frac{7}{5}\)

\(\frac{1999.2000-1}{1998+1999.2000}.\frac{7}{5}\)

= \(\frac{-1}{1998}\) . \(\frac{7}{5}\)

= \(\frac{-7}{9990}\)

\(\frac{1999.2000+1999}{1998+1999.2000}.\frac{7}{5}=1+\frac{1}{1998+1999.2000}.\frac{7}{5}=1+\frac{7}{5.\left(1998+1999.2000\right)}=1+\frac{7}{19999990}=\frac{19999997}{19999990}\)

nhầm:mux3=mũ3

là số nguyên tố 

1998 + 2000 + 2 = ( 1998 + 2 ) + 2000

                        = 2000 + 2000

                        = 4000

1999 x 1999 + 1 = 3996002

1998 + 2000 + 2 / 1999 x 1999 + 1 = 4001

là 4000000 đó nha

ra số thập phân

nhưng bằng bao nhiu hả bạn ???

\(\frac{1999\cdot2001-1}{1998+1999\cdot2000}\cdot\frac{7}{5}\)

\(=\frac{1999\cdot\left(2000+1\right)-1}{1998+1999\cdot2000}\cdot\frac{7}{5}\)

\(=\frac{1999\cdot2000+1999-1}{1998+1999.2000}\cdot\frac{7}{5}\)

\(=\frac{1999\cdot2000+1998}{1998+1999.2000}\cdot\frac{7}{5}=1\cdot\frac{7}{5}=\frac{7}{5}\)

thank you very much

1999.2001-1/1998+1999.2000 x 7/5

=1999.2001-(1999-1998)/1998+1999.2000 x7/5

=1999.2001-1999+1998/1998+1999.2000 x7/5

=1999(2001-1)+1998/1998+1999.2000x7/5

=1999.2000+1998/1998+1999.2000x7/5

=1x7/5=7/5

7/9990

ta sẽ vạn ước chúng

=1x2001-1/1998x1x2000x7/5

=1/1998x7/5

=1x7/5x1998

=7/9990

có sai thì thôi nha