Question

Bài 1 : Thực hiện phép tính 

a) \(\dfrac{19}{12}\) + | \(\dfrac{-5}{2}\) | + ( \(\dfrac{3}{2}\) )²

b) \(\dfrac{2}{11}\) . \(\dfrac{16}{9}\) -  \(\dfrac{2}{11}\) . \(\dfrac{7}{9}\)

Bài 2 : Tìm x , biết 

\(\dfrac{a}{8}\) = \(\dfrac{b}{3}\) và a - b = 55

Answer 1

Bài 1:

a) \(\dfrac{19}{12}+\left|\dfrac{-5}{2}\right|+\left(\dfrac{3}{2}\right)^2=\dfrac{19}{12}+\dfrac{5}{2}+\dfrac{9}{4}\)

\(=\dfrac{19+5.6+9.3}{12}=\dfrac{76}{12}=\dfrac{19}{3}\)

b) \(\dfrac{2}{11}.\dfrac{16}{9}-\dfrac{2}{11}.\dfrac{7}{9}=\dfrac{2}{11}\left(\dfrac{16}{9}-\dfrac{7}{9}\right)=\dfrac{2}{11}.1=\dfrac{2}{11}\)

Bài 2:

Áp dụng t/c dtsbn:

\(\dfrac{a}{8}=\dfrac{b}{3}=\dfrac{a-b}{8-3}=\dfrac{55}{5}=11\)

\(\Rightarrow\left\{{}\begin{matrix}x=11.8=88\\b=11.3=33\end{matrix}\right.\)