bn án vào đúng 0 sẽ ra kết quả mình giải rồi

3962094

           3962088 nhé bạn

1998*1991+3978

=3978018 + 3978

=3981996

Bài 2 :

 1992*1991-3984

 = 3966072-3978

=3962094

=-19916

    1990 x 1990 - 1992 x 1998

= (1992 - 2)x1990 - 1992 x (1990 - 2)

= 1992 x 1990 - 2 x 1990 - 1992 x 1990 + 1992 x 2

= 1992 x 2 - 2 x 1990

= (1992 - 1990) x 2

=       2   x 2 

= 4

mot manh dat hcn dai 48 m. chieu rong bang 3/4 chieu dai nguoi ta trong rau cu 4m thu duoc 10 kg  rau

tinh dien tinh thu duoc 10 kg rau

tinh so kg rau thu duoc

1990 . 1990 - 1992 . 1998

=3 960 100-3 980 016

=-19 916

19991999 . 1998 - 19981998.1999

= 1999 . 1001 . 1998 - 1998 . 1001 . 1999

= 0

tick nhé bạn

19991999 . 1998 - 19981998.1999

= 1999 . 1001 . 1998 - 1998 . 1001 . 1999

= 0

câu thứ nhất bằng 7876638900

câu thứ 2 bằng 798081399759

1990.1990-1992.1988

=1990.(1988+2)-(1990+2).1988

=1990.1988+1990.2-1990.1988+1988.2

= (1990-1988).2

=2.2

=4

\(\Leftrightarrow\left(\dfrac{x-5}{1990}-1\right)+\left(\dfrac{x-15}{1980}-1\right)+\left(\dfrac{x-25}{1970}-1\right)\\ +\left(\dfrac{x-1990}{5}-1\right)+\left(\dfrac{x-1980}{15}-1\right)+\left(\dfrac{x-1970}{25}-1\right)=0\\ \Leftrightarrow\dfrac{x-1995}{1990}+\dfrac{x-1995}{1980}+\dfrac{x-1995}{1970}+\dfrac{x-1995}{5}\\ +\dfrac{n-1995}{15}+\dfrac{n-1995}{25}=0\\ \Rightarrow\left(x-1995\right)\left(\dfrac{1}{1990}+\dfrac{1}{1980}+\dfrac{1}{1970}+\dfrac{1}{5}+\dfrac{1}{15}+\dfrac{1}{25}\right)=0\) 

\(\Rightarrow x-1995=0\\ \Rightarrow x=1995\)

a, 1990 x 1990 - 1992 x 1998

= 1990 x 1990 - ( 1992 - 2 ) x ( 1998 + 2 )

= 1990 x 1990 - 1990 x 2000

= 1990 x ( 2000 - 1990 )

= 1990 x 10

= 19900

a) 1990 x 1990 - 1992 x 1998

=1990 x 1998 - 1992

= 1990 x 6

= 11940

1990 x 1990 - 1992 x 1998

= 1990 x 1990 - ( 1992 - 2 ) x ( 1998 + 2 )

= 1990 x 1990 - 1990 x 2000

= 1990 x ( 2000 - 1990 )

= 1990 x 10

= 19900