sửa đề \(\left(\frac{1}{1+a}+1-a\right):\left(\frac{1}{1-a^2}+1\right)\)đk : xkhác -1 ; 1 

\(=\left(\frac{1+1-a^2}{1+a}\right):\left(\frac{1+1-a^2}{1-a^2}\right)=\frac{2-a^2}{1+a}:\frac{2-a^2}{1-a^2}=\frac{1-a^2}{a+1}=1-a\)

TL: 

a) x - 1/4 = 5/3       

    x         = 1/4 + 5/3 

   x          = 4/6  

b) x - 2/3 = 1/2 

   x          = 2/3 + 1/2 

   x          = 7/6 

k cho mình 

HT

a, X = 5/3 + 1/4 

x = 20/12 + 3/12

X = 23/12

b, X = 1/2+ 2/3

X = 3/6 + 4/6

X = 7/6

a, \(x-\frac{1}{4}=\frac{5}{3}\)

 \(x=\frac{5}{3}-\frac{1}{4}=\frac{20}{12}-\frac{3}{12}\)

\(x=\frac{17}{12}\)

b, \(x-\frac{2}{3}=\frac{1}{2}\)

\(x=\frac{1}{2}+\frac{2}{3}=\frac{3}{6}+\frac{4}{6}\)

\(x=\frac{7}{6}\)

#Fox

\(A.X-\frac{1}{4}=\frac{5}{3}\)

\(X=\frac{5}{3}-\frac{1}{4}=\frac{20}{12}-\frac{3}{12}\)

\(X=\frac{17}{12}\)

\(B.X-\frac{2}{3}=\frac{1}{2}\)

\(X=\frac{1}{2}+\frac{2}{3}=\frac{3}{6}+\frac{4}{6}\)

\(X=\frac{7}{6}\)

_HT_

44/11 = 4 nhé 

TL:

\(\frac{44}{11}=\frac{44:11}{11:11}=4\)

Nhé

_HT_

\(\frac{3\times145+3\times55}{6\times215+6\times85}\)

\(=\frac{3\times\left(145+55\right)}{6\times\left(215+85\right)}\)

\(=\frac{3\times200}{6\times300}\)

\(=\frac{600}{1800}=\frac{1}{3}\)

#Fox