ĐKXĐ : 2x \(\ge\)0 <=> x \(\ge\)0

| 7 + x | = 2x <=> \(\orbr{\begin{cases}7+x=2x\\7+x=-2x\end{cases}}\)

                     <=> \(\orbr{\begin{cases}x=7\\x=\frac{-7}{3}\end{cases}}\)( KTMĐK)

Vậy x = 7 

a)\(\dfrac{24}{36}\)=\(\dfrac{8}{12}\)

b)\(\dfrac{14}{56}\)=\(\dfrac{1}{4}\)

c)\(\dfrac{9}{24}\)=\(\dfrac{21}{56}\)

Chúc bạn học tốt!

a: x/12=24/36

nên x/12=2/3

=>x=2/3x12=8

b: 1/x=14/56

nên 1/x=1/14

hay x=14

c: x/56=9/24

=>x/56=3/8

hay x=21

ban ghi j minh ko hieu

Ta thấy rằng từ 6 đến y có:\(\frac{y-6}{2}+1=\frac{y-4}{2}\)số

Nên sẽ có: \(\frac{y-4}{4}\)cặp

Theo đề bài ta có:

\(6-8+10-12+...-y=-200\)

\(\Rightarrow\left(6-8\right)+\left(10-12\right)+...+\left(y-2-y\right)=-200\)

\(\Rightarrow-2-2-...-2=-200\) (có \(\frac{y-4}{4}\)số -2)

\(\Rightarrow-2.\frac{y-4}{4}=-200\)

\(\Rightarrow y-4=400\)

\(\Rightarrow y=404\)

\(A=2+2^2+2^3+2^4+...+2^{99}+2^{100}\)

\(\Rightarrow A=\left(2+2^2\right)+\left(2^3+2^4\right)+...+\left(2^{99}+2^{100}\right)\)

\(\Rightarrow A=\left(2+2^2\right)+2^2\left(2+2^2\right)+...+2^{98}\left(2+2^2\right)\)

\(\Rightarrow A=\left(2+2^2\right)\left(1+2^2+...+2^{98}\right)\)

\(\Rightarrow A=6\left(1+2^2+...+2^{98}\right)⋮6\)

\(\Leftrightarrow4,5x-0,5x=2,6\)

\(\Leftrightarrow4x=2,6\)

\(\Leftrightarrow x=0,65\)

Tu so be nhat = 0. Tu so lon nhat = 2009

Co so phan so la: ( 2009 - 0 ) : 1 + 1 = 2010 ( phan so )

                                                     D/s : 2010 phan so

2010 p/số 

1/    166,6666667

2/     333,3333333

3/      500

4/      593,05

5/       583

6/       240000

1.     166,67

2.      333,3

3.      500

4.      593,05

5.      583

6.      240000

nha cậu