Tinh gia tri bieu thuc:

\(D=\left(\frac{3}{2}\right)^2+\left(\frac{1}{4}\right)^2-\left(\frac{1}{2}\right)^3\)

Tinh gia tri bieu thuc

\(C=\frac{38}{45}-\left(\frac{8}{45}-\frac{17}{51}-\frac{3}{11}\right)\)

\(B=\frac{-2}{3}+\frac{3}{4}-\frac{-1}{6}+\frac{-2}{5}\)

TInh gia tri bieu thuc

\(B=\frac{-2}{3}+\frac{3}{4}-\frac{-1}{6}+\frac{-2}{5}\)

Tinh gia tri bieu thuc :

\(A=\frac{3}{18\cdot21}+\frac{3}{21\cdot24}+...+\frac{3}{87\cdot90}\)