Question

[Khánh Linh]

BT1: Tính nhanh:

1) (\(\dfrac{12}{23}+\dfrac{12}{2323}-\dfrac{121212}{232323}\)) . ( \(\dfrac{1}{3}+\dfrac{1}{4}\) - \(\dfrac{7}{12}\))

Answer 1

[Bùi Ngọc Minh]

Gọi \(\dfrac{12}{23}+\dfrac{12}{2323}-\dfrac{121212}{232323}\) là A

Ta sẽ tính biểu thức A.\(\left(\dfrac{1}{3}+\dfrac{1}{4}-\dfrac{7}{12}\right)\)=A.\(\left(\dfrac{7}{12}-\dfrac{7}{12}\right)=0\)

Vậy \(\left(\dfrac{12}{23}+\dfrac{12}{2323}-\dfrac{121212}{232323}\right).\left(\dfrac{1}{3}+\dfrac{1}{4}-\dfrac{7}{12}\right)\)=0