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

\(=\dfrac{399\times100}{1995\times5}=\dfrac{399\times20}{1995}=\dfrac{7980}{1995}=4\)

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

399x45+55x399

=399x(45+55)

=399x100

=39900

câu sau mình ko bít làm

câu sau là: 1995 x 1996- 1991 x 1995

=1995 x ( 1996 - 1991)

=1995 x 5

=9980

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

399*45+55*399=399*100=39900

1994*1996-1991*1995

=1995^2-1-1991*1995

=1995*4-1

=7979

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

\(399\times45+55\times399=399\times\left(45+55\right)=399\times100\)                 (1)

\(1995\times1996-1991\times1995=1995\times\left(1996-1991\right)\) 

\(=1995\times5=\left(2000-5\right)=\left(400\times5\right)-1\times5=5\times\left(400-1\right)=5\times399\)   (2)

Từ (1) và (2) \(\Rightarrow\dfrac{399\times100}{399\times5}=\dfrac{100}{5}=20\)

A = 1995×1996−1991×1995

A= 1995 x ( 1996 - 1991)

A= 1995 x 1995

A= 39800253980025

Số to quá e ạ
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\(\frac{399\cdot45+55\cdot399}{1995\cdot1996-1991\cdot1995}\)

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

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 !

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

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

a, 399.45 + 55.399                                                                  

= 399 ( 45 + 55 )

= 399.    100

=     39900

b, 1995.1996 - 1991.1995

= 1995 ( 1996 - 1991 )

= 1995 .     5

=      9975

A)399x45+55x399

=399x(45+55)

=399x100

=3990

b)1995.1996-1991.1995

=1995.(1996-1991)

=1995.5

=9975

a)=39900