Question

Tìm x thuộc Q biết rằng 

a, 11/12-(2/5+x) = 2/3

b, 2x.(x-1/7)=0

c,3/4+1/4:x=2/5

Answer 1

a)\(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{3}\)

<=>\(\frac{11}{12}-\frac{2}{5}-x=\frac{2}{3}\)

<=>\(-x=\frac{2}{3}-\frac{11}{12}+\frac{2}{5}\)

<=>\(-x=\frac{3}{20}\)

<=>\(x=-\frac{3}{20}\)

b)\(2x\left(x-\frac{1}{7}\right)=0\)

<=>2x=0 hoặc \(x-\frac{1}{7}=0\)

<=>x=0 hoặc x=\(\frac{1}{7}\)

c)\(\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\)

<=>\(\frac{1}{4}:x=\frac{2}{5}-\frac{3}{4}\)

<=>\(\frac{1}{4}:x=-\frac{7}{20}\)

<=>\(x=\frac{1}{4}:\left(-\frac{7}{20}\right)\)

<=>\(x=-\frac{5}{7}\)