Tìm x, biết:
(x+2)/2012+(x+2)/2011+...+(x+2)/1996=(x+2)/1995+(x+2)/1994+...+(x+2)/1002
Tìm x, biết x+1/1999+x+2/1998+x+3/1997=x+4/1996+x+4/1995+x+6/1994
Suy ra \(\frac{x+1}{1999}+1+\frac{x+2}{1998}+1=\frac{x+3}{1997}+1+\frac{x+4}{1996}\)
Suy ra \(\frac{x+2000}{1999}+\frac{x+2000}{1998}=\frac{x+2000}{1997}+\frac{x+2000}{1996}\)
Suy ra \(\frac{x+2000}{1999}+\frac{x+2000}{1998}-\frac{x+2000}{1997}-\frac{x+2000}{1996}=0\)
Suy ra \(x+2000.\left(\frac{1}{1999}+\frac{1}{1998}-\frac{1}{1997}-\frac{1}{1996}\right)=0\)
Vì \(\left(\frac{1}{1999}+\frac{1}{1998}-\frac{1}{1997}-\frac{1}{1996}\right)\ne0\)
Suy ra x+2000=0
Suy ra x=-2000
Hok tốt
Giải bất phương trình sau:
\(\frac{x+1994}{2009}+\frac{x+1995}{2010}>\frac{x+1996}{2011}+\frac{x+1997}{2012}\)
a,x-10/1994+x-8/1996+x-6/1998+x-4/2000+x-2/2002=x-2002/2+x-2000/4+x-1998/6+x-1996/8+x-1994/10
b,x-1991/9+x-1993/7+x-1995/5+x-1997/3+x-1999/1=x-9/1991+x-7/1993+x-5/1995+x-3/1997+x-1/1999
c,x-1/13-2x-13/15=3x-15/27-4x-27/29
Bài 2 tính nhanh a,15 x 2121/4343 + 15 x 222222/434343 b,399 x 45 + 55 x 399/1995 x 1996 - 1991 x 1995 c,1996 x 1995 - 996/1000 + 1996 x 1994 d,637 x 527 - 189/526 x 637 + 448 e,677 x 874 + 251/678 x 874 - 623 khẩn cấp huhuhu.......... aaaaaaaaaa
a, 15(21/43+22/43)=15.1=15
b, 399(45+55) / 1995(1996-1991)
=399.100 / 1995.5
=4
Tính nhanh
a)399 x 45 +55 x 399/ 1995x 1996 - 1991 x 1995 b) 1996 x 1995 - 996/ 1000+ 1996 x 1994
Bạn nào giải được đầy đủ , đúng Nhung sẽ tịk 2 cái cho
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!
Tính nhanh :
1 . ( 19 x 43 - 26928 : 33 ) x ( 16112 : 53 - 10,1 x 30 )
2. 1996 x 1995 - 996 + 1000 - 1996 x 1994
3. ( 1 + 2 + 4 + ... + 512 ) x ( 101 x 102 - 101 x 101 - 50 - 51 )
4. 10,09 x 100 + 2009 + 200,9 : 0,1 + 2,009 : 0,001
1=ĐS=1
2=ĐS=2000
3=ĐS=0
4=ĐS=7036
K MÌNH NHA
Tìm x : (x - 5) x (1995 x 1996 + 1996 x 1997) = 1234 x 5678 x (630 - 315 x 2) : 1996
a,1997 x 1996 - 1
----------------------------
1995 x 1997 + 1996
b,1997 x 1996 - 995
-----------------------------------------
1995 x 1997 + 1002
giúp em với ạ
a) \(\dfrac{1997x1996-1}{1995x1997+1996}=\dfrac{1997x\left(1995+1\right)-1}{1995x1997+1996}\)
\(=\dfrac{1997x1995+1997-1}{1995x1997+1996}=\dfrac{1997x1995+1996}{1995x1997+1996}=1\)
b) \(\dfrac{1997x1996-995}{1995x1997+1002}=\dfrac{1997x\left(1995+1\right)-995}{1995x1997+1002}\)
\(=\dfrac{1997x1995+1997-995}{1995x1997+1002}=\dfrac{1997x1995+1002}{1995x1997+1002}=1\)
x-10/1994+X-8/1996+X-6/1998/+ X-4/2000+X-2/2002=X-2002/2+X-2000/4+X-1998/6+X-1996/8+X-1994/10
(X -10/1994 -1) + (X-8/1996 - 1) + (X-6/1998 - 1)+ (X-4/2000 - 1) + (X-2/2002 - 1) = (X-2002/2 - 1) + (X-2000/4 - 1) + (X-1998/6 - 1) + (X-1996/8 - 1) + (X-1994/10 - 1)
=> x-2004/1994 + x-2004/1996 + x-2004/1998 + x-2004/2000 + x-2004/2002 = x-2004/2 + x-2004/4 + x-2004/6 + x-2004/8 + x-2004/1994
=> x-2004/1994 + x-2004/1996 + x-2004/1998 + x-2004/2000 + x-2004/2002 - x-2004/2 - x-2004/4 - x-2004/6 - x-2004/8 - x-2004/1994 = 0
=> (x - 2004)(1/994 + 1/1996 + 1/1998 + 1/2000 + 1/2002 + 1/2 + 1/4 + 1/6 + 1/8) = 0
Mà (1/994 + 1/1996 + 1/1998 + 1/2000 + 1/2002 + 1/2 + 1/4 + 1/6 + 1/8) \(\ne\)0
=> x - 2004 = 0
=> x = 2004
Vậy x = 2004
Sửa (x - 2004) (1/1994 + 1/1996 + 1/1998/+ 1/2000 + 1/2002 + 1/2 + 1/4 + 1/6+ 1/8 + 1/10)
= (x - 2004) (1/1994 + 1/1996 + 1/1998/+ 1/2000 + 1/2002 - 1/2 -1/4 - 1/6 - 1/8 - 1/10)
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