Câu 9.
a) \(\dfrac{3}{7}+(-\dfrac{5}{2}).(-\dfrac{4}{3})\)
\(=\dfrac{3}{7}+\dfrac{20}{6}\)
\(=\dfrac{18}{42}+\dfrac{140}{42}\)
\(=\dfrac{158}{42}\)
\(=\dfrac{79}{21}\)
b) \(\dfrac{4^4.2^5}{2^{11}}\)
\(=\dfrac{2^8.2^5}{2^{11}}\)
\(=\dfrac{2^{13}}{2^{11}}\)
\(=2^2\)
\(=4\)
Câu 10.
a) \(x-5=\dfrac{2}{3}\)
\(x=\dfrac{2}{3}+5\)
\(x=\dfrac{17}{3}\)
b) \(x:(-\dfrac{1}{2})^3=-\dfrac{1}{2}\)
\(x=(-\dfrac{1}{2}).(-\dfrac{1}{2})^3\)
\(x=(\dfrac{1}{2})^4\)
\(x=\dfrac{1}{16}\)
