Question

tìm x , biết :

a . ( x -2,5 ) : 2 1/2 - 2,5 = -1 1/4

b . ( 2,5 x - 3,6 ) : 1 5/7 = -1

c . ( 3 3/4 - 2x ) . 1 1/3 = 2 1/9

Answer 1

a: \(\Leftrightarrow\left(x-\dfrac{2}{5}\right):\dfrac{3}{2}=-\dfrac{5}{4}+\dfrac{5}{2}=\dfrac{5}{4}\)

\(\Leftrightarrow x-\dfrac{2}{5}=\dfrac{5}{4}\cdot\dfrac{3}{2}=\dfrac{15}{8}\)

hay x=91/40

b: \(\Leftrightarrow\left(2.5x-3.6\right)=-1\cdot\dfrac{12}{7}=\dfrac{-12}{7}\)

=>2,5x=66/35

hay x=132/175

c: \(\Leftrightarrow\left(\dfrac{15}{4}-2x\right)=\dfrac{19}{9}:\dfrac{4}{3}=\dfrac{19}{9}\cdot\dfrac{3}{4}=\dfrac{19}{12}\)

=>2x=15/4-19/12=45/12-19/12=26/12

=>x=13/12