Question

Tìm x thuộc Z biết:

a. x-3/4=15/20

b.x/9=4/x

Answer 1

a) \(x-\frac{3}{4}=\frac{15}{20}=\frac{3}{4}\)

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

b) \(\frac{x}{9}=\frac{4}{x}\Rightarrow x^2=36=6=-6\)

\(\Rightarrow x=\hept{\begin{cases}6\\-6\end{cases}}\)

Answer 2

a) \(x-\frac{3}{4}=\frac{15}{20}\)

\(\Rightarrow x=\frac{15}{20}+\frac{3}{4}\)

\(\Rightarrow x=\frac{3}{2}\)

b) \(\frac{x}{9}=\frac{4}{x}\)

\(\Rightarrow x^2=36\)

\(\Rightarrow x=6\)

Answer 3

a. x  = 15/20 + 3/4

    x  =   15/20 + 15/20

    x  =      3/2

b. x/9 = 4/x

=> x nhân x =  9 x 4

     x mũ 2  =  36

     x mũ 2  =  6 mũ 2

 =>   x = 6