\(x^3-12x^2+48x-72=0\)

a)

*=2 và 5

b)

*=2 và 8

c)

*=0

d)

*=5

lộn thì chị 

sao anh bấm máy nhanh vậy :)))

\(15:x=5\)

\(x=15:5=3\)

b)

\(\dfrac{x}{4}=3\)

\(\dfrac{x}{4}=\dfrac{3}{1}=>\dfrac{x}{4}=\dfrac{12}{4}\)

\(=>x=12\)

c)

\(\dfrac{21}{x}=7=>\dfrac{21}{x}=\dfrac{7}{1}=>\dfrac{21}{x}=\dfrac{21}{3}\)

\(=>x=3\)

\(a:\dfrac{1}{6}=\dfrac{1}{3}-\dfrac{1}{5}\)

\(a:\dfrac{1}{6}=\dfrac{2}{15}\)

\(a=\dfrac{2}{15}\cdot\dfrac{1}{6}=\dfrac{1}{45}\)

\(\dfrac{2}{5}-\left(\dfrac{4}{3}+\dfrac{4}{5}\right)-\left(-\dfrac{1}{9}-0,4\right)+\dfrac{11}{9}\)

\(=\dfrac{2}{5}-\dfrac{4}{3}-\dfrac{4}{5}+\dfrac{1}{9}+\dfrac{2}{5}+\dfrac{11}{9}\)

\(=\left(\dfrac{2}{5}-\dfrac{4}{5}+\dfrac{2}{5}\right)+\left(-\dfrac{4}{3}+\dfrac{1}{9}+\dfrac{11}{9}\right)\)

\(=0+0=0\)

\(\dfrac{7}{12}-\dfrac{57}{36}\cdot\dfrac{-6}{19}+\dfrac{-1}{42}:\dfrac{-5}{7}\)

\(\dfrac{7}{12}-\dfrac{-1}{2}+\dfrac{1}{30}=\dfrac{67}{60}\)

\(a\cdot\dfrac{1}{6}=\dfrac{1}{12}\)

\(a=\dfrac{1}{12}:\dfrac{1}{6}\)

\(a=\dfrac{1}{12}\cdot6\)

\(a=\dfrac{1}{2}\)