1994 x 1993 - 2/1992+ 1992 x1994 1993 x 19941994/19931993 x 1994
Tính nhanh: 1994 x 1993 - 1992 x 1993/ 1992 x 1993 + 1994 x 7 + 1986
B= 1991/1990 x 1992/1991 x 1993/1992 x 1994/1993 x 995/997
B= 1991/1990 x 1992/1991 x 1993/1992 x 1994/1993 x 995/997
\(B=\dfrac{1991}{1990}\cdot\dfrac{1992}{1991}\cdot\dfrac{1993}{1992}\cdot\dfrac{1994}{1993}\cdot\dfrac{995}{997}\)
\(=\dfrac{1991}{1991}\cdot\dfrac{1992}{1992}\cdot\dfrac{1993}{1993}\cdot\dfrac{1994}{1990}\cdot\dfrac{995}{997}=\dfrac{997}{995}\cdot\dfrac{995}{997}=1\)
B= 1991/1990 x 1992/1991 x 1993/1992 x 1994/1993 x 995/997
Tính nhnh
C) 1994 x 1993 - 1992 x 1993 / 1992 x 1993 x 7 + 1986
1991/1990 x 1992/1991 x 1993/1992 x 1994 /1993 x 995/997
A = \(\dfrac{1991}{1990}\) x \(\dfrac{1992}{1991}\) x \(\dfrac{1993}{1992}\) x \(\dfrac{1994}{1993}\) x \(\dfrac{995}{997}\)
A = \(\dfrac{1991\times1992\times1993\times997\times2\times995}{995\times2\times1991\times1992\times1993\times997}\)
A = 1
1991/1990 x 1992/1991 x 1993/1992 x 1994/1993 x 995/997
tính bằng cách thuận tiện nhất
Tính nhnh
C) 1994 x 1993 - 1992 x 1993 / 1992 x 1993 x 7 + 1986
1993 x ( 1994 - 1992 ) 1992 x ( 1993 + 7 )
= 1993 x 2 =1992 x 2000
= 3986 =398
4
x
1986
=
791
2
2
2
4
Thực hiện phép tính
(x-1)(x^1994+x^1993+x^1992+x^1991+...+x^2+x+1)
(x+1) (x^1994-x^1993-x^1992-x^1991-...-x^2-x+1)
Giúp mk nha, mkcânf gấp