b. 399 x 45 + 55 x 399

= 399 x ( 45 +55 )

= 399 x 100

39900

1995 x 1996 - 1991 x 1995

= 1995 x ( 1996 - 1991 )

= 1995 x 5

= 9975

a) 399(45+55) / 1995(1996-1991)

=39900 / 9975

=4

b) 

a) \(\frac{399\cdot45+55\cdot399}{1995\cdot1996-1991\cdot1995}\)

\(=\frac{399\cdot\left(45+55\right)}{1995\cdot\left(1996-1991\right)}\)

\(=\frac{399\cdot100}{1995\cdot5}\)

\(=4\)

=))

\(a,\frac{399×\left(45+55\right)}{1995×\left(1996-1991\right)}\)

\(=\frac{39900}{9975}\)

\(=4\)

a) 399(45+55) / 1995(1996-1991)

=39900 / 9975

=4

a) \(\frac{399\cdot45+55\cdot399}{1995\cdot1996-1991\cdot1995}\)

\(=\frac{399\cdot\left(45+55\right)}{1995\cdot\left(1996-1991\right)}\)

\(=\frac{399\cdot100}{1995\cdot5}\)

\(=4\)

=))

b) 1000.1995+1995.996-996

    1000+1000.1994+1994.996

=1000.1995+996.1994

   1000.1995+996.1994

=1

\(\frac{399\cdot45+55\cdot399}{1995\cdot1996-1991\cdot1995}\)

\(=\frac{399\cdot(45+55)}{1995\cdot(1996-1991)}=\frac{399\cdot100}{1995\cdot5}=\frac{1\cdot20}{5\cdot1}=\frac{20}{5}=4\)

Trả lời

399.45+55.399/1995.1996-1991.1995

=399.(45+55)/1995.(1996-1991)

=399.20.5/399.5.5

=20/5

=4/1=4.

Hok chắc !

\(\frac{399\times45+55\times399}{1995\times1996-1991\times1995}\)

\(=\frac{399\left(45+55\right)}{1995\left(1996-1991\right)}=\frac{100}{5.5}=4\)

`(399 xx 45 + 55 xx 399)/(1995xx1996-1991xx1995)`

`= (399xx(45+55))/(1995xx(1996-1991))`.

`= (399xx100)/(1995xx5)`

`= (399 xx 5 xx 5 xx 4)/(1995 xx 5)`

`= 4`.

\(\dfrac{399\times45+55\times399}{1995\times1996-1991\times1995}\)

\(=\dfrac{399\times\left(45+55\right)}{1995\times\left(1996-1991\right)}\)

\(=\dfrac{399\times100}{1995\times5}\)

\(=\dfrac{399\times5\times5\times4}{399\times5\times5}\)

\(=\dfrac{1\times1\times1\times4}{1\times1\times1}\)

\(=4\)

399 x 45 x 399 : 1995 x 1996 - 1991 x 1995

= 3195591

1996 x 1995 - 996 : 1000 + 1996 x 1994

= 7962043.004

Làm lại nhé:

399 x 45 + 55 x \(\frac{399}{1995}\) x 1996 - 1991 x 1995

= -3932134

1996 x 1995 - \(\frac{996}{1000}\)+ 1996 x 1994

= 7962043.004

Đề bài sai hay sao ấy!

tất cả đều đặt nhân tử chung bạn ạ

a, 399 x45 + 55x 399 = 399 x (45+55) = 399x 100

1995 x 1996 - 1991x1995= 1995x (1996-1991)=1995 x 5 = 2000 -5= (400 x5) - 1 x 5= 5x (400-1) = 5*399

nên đáp án là bằng 100/5 = 20

hai câu sau làm tương tự , ahihi

theo mình Nguyễn Như Quỳnh làm sai rồi

399 x 45 + 55 x 399 / 1995 x 1996 - 1991 x 1995 = 399 x (45+55) / 1995 x (1996-1991)=399 x 100 / 1995 x 5=399 x 100/ 399x5x5=399x100/399x25=100/25=4

các bạn thấy mình đúng thì k cho mình nha !

ahihi đồ ngu

a, 15(21/43+22/43)=15.1=15

b, 399(45+55) / 1995(1996-1991)

=399.100 / 1995.5

=4

 de ma . k cho minh va ket ban roi minh giai cho : 

\(\frac{399.45+55.399}{1995.1996-1991.1995}\)

\(=\frac{399.\left(45+55\right)}{1995.\left(1996-1991\right)}\)

\(=\frac{399.100}{1995.5}\)

\(=\frac{399.2^2.5.5}{399.5.5}\)

\(=\frac{2^2}{1}=4\)