a) 500

b) 2303                

c) 537                  

d) 35000

e) 90000

f) 380

a) \(\frac{x+1}{2004}+\frac{x+2}{2003}=\frac{x+3}{2002}+\frac{x+4}{2001}\)

\(\Leftrightarrow\frac{x+2005}{2004}+\frac{x+2005}{2003}=\frac{x+2005}{2002}+\frac{x+2005}{2001}\)

\(\Leftrightarrow\left(x+2005\right)\left(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\right)=0\)

\(\Leftrightarrow x+2005=0\)

\(\Leftrightarrow x=-2005\)

b) Sửa đề :

\(\frac{201-x}{99}+\frac{203-x}{97}+\frac{205-x}{95}+3=0\)

\(\Leftrightarrow\frac{300-x}{99}+\frac{300-x}{97}+\frac{300-x}{95}=0\)

\(\Leftrightarrow\left(300-x\right)\left(\frac{1}{99}+\frac{1}{97}+\frac{1}{95}\right)=0\)

\(\Leftrightarrow x=300\)

c) \(\frac{2-x}{2002}-1=\frac{1-x}{2003}-\frac{x}{2004}\)

\(\Leftrightarrow\frac{2-x}{2002}+1=\frac{1-x}{2003}+1-\frac{x}{2004}+1\)

\(\Leftrightarrow\frac{2004-x}{2002}=\frac{2004-x}{2003}-\frac{2004-x}{2004}\)

\(\Leftrightarrow\left(2004-x\right)\left(\frac{1}{2002}-\frac{1}{2003}+\frac{1}{2004}\right)=0\)

\(\Leftrightarrow x=2004\)

Vậy....

a) \(\dfrac{x+1}{2004}+\dfrac{x+2}{2003}=\dfrac{x+3}{2002}+\dfrac{x+4}{2001}\) 

⇔ \(\dfrac{x+1}{2004}+1+\dfrac{x+2}{2003}+1=\dfrac{x+3}{2002}+1+\dfrac{x+4}{2001}+1\)

⇔ \(\dfrac{x+2005}{2004}+\dfrac{x+2005}{2003}=\dfrac{x+2005}{2002}+\dfrac{x+2005}{2001}\)

⇔ \(\left(x+2005\right)\left(\dfrac{1}{2004}+\dfrac{1}{2003}-\dfrac{1}{2002}-\dfrac{1}{2001}\right)\)=0

Vì\(\left(\dfrac{1}{2004}+\dfrac{1}{2003}-\dfrac{1}{2002}-\dfrac{1}{2001}\right)\)<0 nên phương trinh đã cho tương đương:

x+2005=0 ⇔x=-2005

b) \(\dfrac{201-x}{99}+\dfrac{203-x}{97}+\dfrac{205-x}{95}+3=0\) 

⇔ \(\dfrac{201-x}{99}+1+\dfrac{203-x}{97}+1+\dfrac{205-x}{95}+1=0\)

⇔ \(\dfrac{300-x}{99}+\dfrac{300-x}{97}+\dfrac{300-x}{95}=0\)

⇔ \(\left(300-x\right)\left(\dfrac{1}{99}+\dfrac{1}{97}+\dfrac{1}{95}\right)=0\)

Vì \(\left(\dfrac{1}{99}+\dfrac{1}{97}+\dfrac{1}{95}\right)>0\) nên phương trình đã cho tương đương:

300-x=0 ⇔ x=300

44

tuổi ủng hộ mk nha

xin loi minh moi hok lop 6

1. là -2005

2 làm tròn là 49,8

Bất phương trình là sao hả bạn? Có dấu ''='' à?

xin lỗi mình viết lộn

2 -x/2002 + 1 -1 = 1-x/2003 + 1 - x/2004 + 1

=> 2004 - x/ 2002 = 2004 - x/ 2003 + 2004 -x/2004

=> (2004 -x) ( 1/2002-1/2003-1/2004)

ta thấy ( 1/2002-1/2003-1/2004) # 0

=> 2004 -x = 0 => x = 2004

a)\(\dfrac{201-x}{99}+\dfrac{203-x}{97}=\dfrac{205-x}{95}+3=0\)

<=>\(\left(\dfrac{201-x}{99}+1\right)+\left(\dfrac{203-x}{97}+1\right)+\left(\dfrac{205-x}{95}+1\right)=0\)

<=>\(\dfrac{201-x+99}{99}+\dfrac{203-x+97}{97}=\dfrac{205-x+95}{95}=0\)

<=> \(\dfrac{300-x}{99}+\dfrac{300-x}{97}=\dfrac{300-x}{95}=0\)

<=> \(\left(300-x\right)\left(\dfrac{1}{99}+\dfrac{1}{97}+\dfrac{1}{95}\right)=0\)

<=> 300 - x = 0

<=> x = 300

b) \(\dfrac{2-x}{2002}-1=\dfrac{1-x}{2003}-\dfrac{x}{2004}\)

<=> \(\dfrac{2-x}{2002}+1=\left(\dfrac{1-x}{2003}+1\right)+\left(\dfrac{x}{2004}+1\right)\){Cộng cả hai vế của phương trình với 2}

<=> \(\dfrac{2-x+2002}{2002}=\dfrac{1-x+2003}{2003}+\dfrac{-x+2004}{2004}\)

<=> \(\dfrac{2004-x}{2002}=\dfrac{2004-x}{2003}+\dfrac{2004-x}{2004}\)

<=> \(\dfrac{2004-x}{2002}-\dfrac{2004-x}{2003}-\dfrac{2004-x}{2004}=0\)

<=> \(\left(2004-x\right)\left(\dfrac{1}{2002}-\dfrac{1}{2003}-\dfrac{1}{2004}\right)=0\)

<=> 2004 - x = 0

<=> x = 2004.

b) \(\dfrac{2-x}{2002}+\dfrac{x}{2004}-1=\dfrac{1-x}{2003}\)

\(\Leftrightarrow\dfrac{2-x}{2002}+1+\dfrac{x}{2004}-1=\dfrac{1-x}{2003}+1\)( cộng 2 vế cho 1)

\(\Leftrightarrow\dfrac{2-x+2002}{2002}+\dfrac{x-2004}{2004}=\dfrac{1-x+2003}{2003}\)

\(\Leftrightarrow\dfrac{2004-x}{2002}+\dfrac{x-2004}{2004}=\dfrac{2004-x}{2003}\)

\(\Leftrightarrow-\dfrac{x-2004}{2002}+\dfrac{x-2004}{2004}+\dfrac{x-2004}{2003}=0\)

\(\Leftrightarrow\left(x-2004\right)\left(\dfrac{-1}{2002}+\dfrac{1}{2004}+\dfrac{1}{2003}\right)=0\)

\(\Rightarrow x=2004\) do \(\left(\dfrac{-1}{2002}+\dfrac{1}{2004}+\dfrac{1}{2003}\ne0\right)\)

a)95*(100-75)=95*(100-75)           b)2003+10*15=2003+10*3*5

A) 95.(a-75)=95.(100-75)

=>a-75=100-75

vậy a =100

B) 2003+a.15=2003.10.3.5

        a.15=10.3.5

xl bạn chưa xong

a.15=10.(3.5)

a.15=10.15

vậy a=10