1995 * 1994 - 1 / 1993 * 1995 + 1994

= 1995 * 1994 - 1 / ( 1994 -1 ) * 1995 + 1994

= 1995 * 1994 - 1 / 1994 * 1995 - 1995 + 1994

= 1995 * 1994 - 1 / 1994 * 1995 - 1

= 1

nhấn đúng cho mk nha

Tính nhanh giá trị biểu thức :

   1995 x 1994 - 1 / 1993 x 1995 + 1994

= 1995 x 1994 - 1 /  ( 1994 - 1 ) x 1995 + 1994

= 1995 x 1994 - 1 / 1994 x 1995 - 1995 + 1994

= 1995 x 1884 - 1 / 1994 x 1995 - 1

= 1

\(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}\)

\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{6}{11}\frac{16}{11}\right)+\left(\frac{7}{13}+\frac{19}{13}\right)\)

\(=1+2+2\)

\(=5\)

a

        [3/5+2/5]+[7/13+19/13]+[6/11+16/11]=5

Hãy đặt lại biểu thức:

\(\dfrac{1995}{1997}x\dfrac{1997}{54}x\dfrac{27}{45}x\dfrac{90}{1993}x\dfrac{1993}{1995}\)

= \(\dfrac{1}{1}x\dfrac{1}{2}x\dfrac{1}{1}x\dfrac{2}{1}x\dfrac{1}{1}=\dfrac{2}{2}=1\) (Thực hiện gạch)

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, 2006 x 2004 - \(\frac{2}{1995}\) + 2004 x 2005 = 8038043,999

b, 2006 x 125 + \(\frac{1000}{126}\) x 2006 - 1006 = 265664,6349

c, A = 1991 x 1999

=> A = ( 1995 - 4 ) x ( 1995 + 4 )

     A = 1995 x ( 1995 + 4 ) - 4 x ( 1995 + 4 )

     A = 1995 x 1995 + 1995 x 4 - ( 4 x 1995 + 4 x 4 )

     A = 1995 x 1995 - 4 x 4

mà B = 1995 x 1995

Vậy A < B

d, Gọi giá trị biểu thức là C

C =  \(\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}+\frac{1}{96}\) 

C x 2 = \(\frac{2}{3}+\frac{2}{6}+\frac{2}{12}+\frac{2}{24}+\frac{2}{48}+\frac{2}{96}\)

C x 2 = \(\frac{2}{3}+\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}\)

Vậy C x 2 - C = \(\left(\frac{2}{3}+\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}\right)-\left(\frac{1}{3}+\frac{1}{6}+\frac{1}{12}+\frac{1}{24}+\frac{1}{48}+\frac{1}{96}\right)\)

                  C = \(\frac{2}{3}-\frac{1}{96}\) ( vì phân số nào có ở số bị trừ cũng có ở số trừ thì trừ hết rồi nên không còn )

                  C = \(\frac{21}{32}\)

A=1991x1999=(1995-4)1999=1995x1999-4x1999

B=1995x1995=1995x(1999-4)=1995x1999-1995x4>1995x1999-4x1999=A

vậy A<B

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