Question

Tính hợp lí:

a) \(A=\left(\frac{3}{4}-\frac{4}{7}-\frac{5}{6}\right):\left(-\frac{3}{10}+\frac{4}{14}-\frac{-5}{12}\right)\left(\frac{1}{12}-\frac{7}{6}\right)\)

b) 123.(-234+4356-2312)+234.(123-2312)-2312.(-234-123)

Answer 1

a: \(A=\dfrac{63-48-70}{84}:\dfrac{-3\cdot84+4\cdot60+5\cdot70}{840}\cdot\dfrac{1-14}{12}\)

\(=\dfrac{-55}{84}\cdot\dfrac{840}{338}\cdot\dfrac{-13}{12}=\dfrac{55}{1}\cdot\dfrac{10}{338}\cdot\dfrac{13}{12}=\dfrac{275}{156}\)

b: \(=-234\cdot123+123\cdot4356-123\cdot2312+234\cdot123-234\cdot2312+2312\cdot234+2312\cdot123\)

\(=123\cdot4356-123\cdot2312+123\cdot2312=123\cdot4356=535788\)