khoahoc.vietjack.com

Câu hỏi:

14/08/2026 702 Lưu

Cho A= (12/61- 31/22+14/91).(1/2-1/3-1/6), B=3/5: 91/2. 3/5) . Khi đó tổng A + B bằng:

Quảng cáo

Trả lời:

verified Giải bởi Vietjack

Đáp án đúng là: C

\({\rm{A}} = \left( {\frac{{12}}{{61}} - \frac{{31}}{{22}} + \frac{{14}}{{91}}} \right) \cdot \left( {\frac{1}{2} - \frac{1}{3} - \frac{1}{6}} \right)\)

\( = \left( {\frac{{12}}{{61}} - \frac{{31}}{{22}} + \frac{{14}}{{91}}} \right) \cdot \left( {\frac{3}{6} - \frac{2}{6} - \frac{1}{6}} \right) = \left( {\frac{{12}}{{61}} - \frac{{31}}{{22}} + \frac{{14}}{{91}}} \right) \cdot 0 = 0\)

\({\rm{B}} = \frac{3}{5}:\left( {\frac{1}{2} \cdot \frac{3}{5}} \right) = \frac{3}{5}:\frac{3}{{10}} = \frac{3}{5} \cdot \frac{{10}}{3} = 2\)

A + B = 0 + 2 = 2.