Question

Tìm x, biết:

a)\(\frac{x+1}{2}=\frac{8}{x+1}\)

b)\(x:\left(9\frac{1}{2}-\frac{3}{2}\right)=\frac{0,4+\frac{2}{9}-\frac{2}{11}}{1,6+\frac{8}{9}-\frac{8}{11}}\)

Answer 1

a. \(\frac{x+1}{2}=\frac{8}{x+1}\)

\(\Leftrightarrow\left(x+1\right).\left(x+1\right)=8.2\)

\(\Leftrightarrow\left(x+1\right)^2=16\)

\(\Leftrightarrow\left(x+1\right)^2=2^4\)

\(\Leftrightarrow\left(x+1\right)=2^2\)

\(\Leftrightarrow\left(x+1\right)=4\)

\(\Leftrightarrow x=4-1=3\)

b. \(x:\left(9\frac{1}{2}-\frac{3}{2}\right)=\frac{0,4+\frac{2}{9}-\frac{2}{11}}{1,6+\frac{8}{9}-\frac{8}{11}}\)

\(\Leftrightarrow x:\left(\frac{10}{2}-\frac{3}{2}\right)=\frac{0,4+0,2-0,18}{1,6+0,8-0,72}\)

\(\Leftrightarrow x:\frac{7}{2}=\frac{\frac{21}{50}}{\frac{42}{25}}\)

\(\Leftrightarrow x=\frac{\frac{21}{50}}{\frac{42}{25}}.\frac{7}{2}\Leftrightarrow x=\frac{1}{4}.\frac{7}{2}=\frac{7}{8}\)

Answer 2

a )  \(\frac{x+1}{2}=\frac{8}{x+1}\)

\(\Rightarrow\left(x+1\right).\left(x+1\right)=2.8\)

\(\Rightarrow\left(x+1\right)^2=16\)

\(\Rightarrow\orbr{\begin{cases}x+1=4\\x+1=-4\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=4-1\\x=-4-1\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=3\\x=-5\end{cases}}\)

Dấu " \(\orbr{\begin{cases}\\\end{cases}}\)là hoặc nha !!! 

Answer 3

a)\(\frac{x+1}{2}=\frac{8}{x+1}\)

\(\Rightarrow\left(x+1\right)^2=8\times2=16\)

\(\Rightarrow\left(x+1\right)^2=4^2\)

\(\Rightarrow x+1=4\)

\(\Rightarrow x=4-1=3\)

b)tớ ko biết làm . ~ sorry~

~chuk bn hok giỏi~

Answer 4

câu a mk thiếu \(\orbr{\begin{cases}\left(x+1\right)^2\\\left(x+1\right)^2=4^2\end{cases}}=\left(-4\right)^2\)

Answer 5

a) x+1/2=8/x+1

Suy ra (x+1)(x+1)=2.8

Suy ra (x+1)^2=16

Suy ra (x+1)^2=4^2

Suy ra x+1=4 Suy ra x=3

b) x : (9 1/2-3/2) = 0.4 + 2/9 - 2/11 / 1.6 + 8/9 - 8/11

x: 8= 2/5 + 2/9 - 2/11 / 8/5 + 8/9 + 8/11

x:8= 2 (1/5 + 1/9 - 1/11) / 8 ( 1/5 + 1/9 - 1/11)

x:8=1/4

x=2

Answer 6

a)\(\left(x+1\right).\left(x+1\right)=8.2\)

\(\left(x+1\right)^2=16\)

\(\left(x+1\right)^2=4^2\)

\(x+1=4\)

\(x=4-1\)

\(x=3\)

Answer 7

Ta có : 

\(\frac{x+1}{2}=\frac{8}{x+1}\)

\(\Leftrightarrow\)\(\left(x+1\right)\left(x+1\right)=2.8\)

\(\Leftrightarrow\)\(\left(x+1\right)^2=16\)

\(\Leftrightarrow\)\(x+1=\sqrt{16}=4\)\(\Rightarrow\)\(x=4-1=3\)

Hoặc \(x+1=-\sqrt{16}=-4\)\(\Rightarrow\)\(x=-4-1=-5\)

Vậy \(x=3\) hoặc \(x=-5\)

Chúc bạn học tốt ~

Answer 8

\(\frac{7}{8}\)nha

__________________
__________________
^_^ hok tốt

Answer 9

a) x=3

b)x=2

Answer 10

x+1/2=8/x+1

=>(x+1)^2=2.8

=>(x+1)^2=16

=>(x+1)^2=4^2
=>x+1= 4 hoặc X+1=-4
đến đây rồi thì tự giải nhé

b, x:(9/1/2-3/20=0.4+2/9-2/11  // 1.6+8/9-8/11

x:(19/2-3/2)=2/5+2/9-2/11  // 8/5+8/9-8/11

x: 8= 2(1/5+1/9-1/11)  // 8(1/5+1/9-1/11)

x:8=2/8
x=2/8.8

x=2