\(\dfrac{5}{13}-\dfrac{1}{7}+\dfrac{2}{9}-\dfrac{6}{7}+\dfrac{8}{13}\)

\(=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)-\left(\dfrac{1}{7}+\dfrac{6}{7}\right)+\dfrac{2}{9}\)

\(=\dfrac{13}{13}-\dfrac{7}{7}+\dfrac{2}{9}\)

\(=1-1+\dfrac{2}{9}\)

\(=0+\dfrac{2}{9}\)

\(=\dfrac{2}{9}\)

#Hphong

\(\dfrac{2}{3}.x=-\dfrac{5}{17}\)

\(x=-\dfrac{5}{17}:\dfrac{2}{3}\)

\(x=-\dfrac{5}{17}.\dfrac{3}{2}\)

\(x=-\dfrac{15}{34}\)

#Hphong2010

\(136:x+34:x=10\)

\(\left(136+34\right):x=10\)

\(170:x=10\)

\(x=170:10\)

\(x=17\)

#Hphong

\(70-5.\left(x-3\right)=45\)

\(5.\left(x-3\right)=70-45\)

\(5.\left(x-3\right)=25\)

\(x-3=25:5\)

\(x-3=5\)

\(x=5+3\)

\(x=8\)

#Hphong

3,8 hay 3 và 8?

\(8.\left(3-x\right)=0\)

\(3-x=0:8\)

\(3-x=0\)

\(x=3-0\)

\(x=3\)

#Hphong

\(1-\dfrac{a}{a}=1-1=0\)

\(\Rightarrow\) \(1-\dfrac{a}{a}=0\)

#Hphong

3x + 45 = 25 x 4

3x + 45 = 100

        3x = 100 - 45 

        3x = 55

          x = 55 : 3

          x = \(\dfrac{55}{3}\)

#Hphong

\(4.2^x-3=125\)

\(4.2^x=125+3\) 

\(4.2^x=128\)

\(2^x=128:4\)

\(2^x=32\)

\(2^x=2^5\)

\(\Rightarrow x=5\)

#Hphong