Question

a/\(\left(\dfrac{-3}{7}+\dfrac{5}{11}\right)\):\(\dfrac{-3}{5}\)+\(\left(\dfrac{-9}{7}+\dfrac{6}{11}\right)\):\(\dfrac{-3}{5}\)

b/ \(\left(x-\dfrac{1}{4}\right)^3=27\)

Answer 1

a)\(\left(\dfrac{-3}{7}+\dfrac{5}{11}\right):\dfrac{-3}{5}+\left(\dfrac{-9}{7}+\dfrac{6}{11}\right):\dfrac{-3}{5}\)
=\(\dfrac{2}{77}\):\(\dfrac{-3}{5}+\left(\dfrac{-57}{77}\right):\dfrac{-3}{5}\)
=[\(\dfrac{2}{77}+\left(\dfrac{-57}{77}\right)\)]:\(\dfrac{-3}{5}\)

=\(\left(\dfrac{_{ }-5}{7}\right):\dfrac{-3}{5}\)

=\(\dfrac{25}{21}\)

b)\(\left(x-\dfrac{1}{4}\right)^3=27\)

⇔\(\left(x-\dfrac{1}{4^{ }}\right)^3=3^3\)

⇔\(x-\dfrac{1}{4}=3\)

⇔\(x=3+\dfrac{1}{4}\)

⇔\(x=\dfrac{13}{4}\)

Vậy \(x=\dfrac{13}{4}\)