Advertisements (Quảng cáo)
Tính:
a) \({1 \over 3} + {3 \over 8} – {7 \over {12}}\)
b) \({{ – 3} \over {14}} + {5 \over 8} – {1 \over 2}\)
c) \({1 \over 4} – {2 \over 3} – {{11} \over {18}}\)
d) \({1 \over 4} + {5 \over {12}} – {1 \over {13}} – {7 \over 8}\)
Hướng dẫn làm bài:
a) \({1 \over 3} + {3 \over 8} – {7 \over {12}} = {{8 + 9 – 14} \over {24}} = {3 \over {24}} = {1 \over 8}\)
Advertisements (Quảng cáo)
b) \({{ – 3} \over {14}} + {5 \over 8} – {1 \over 2} = {{ – 12 + 35 – 28} \over {56}} = {{ – 5} \over {56}}\)
c) \({1 \over 4} – {2 \over 3} – {{11} \over {18}} = {{9 – 24 – 22} \over {36}} = {{ – 37} \over {36}}\)
d) \({1 \over 4} + {5 \over {12}} – {1 \over {13}} – {7 \over 8} = {{1 \times 78 + 5 \times 26 – 1 \times 24 – 7 \times 39} \over {312}}\)
\( = {{78 + 130 – 24 – 273} \over {312}} = {{208 – 297} \over {312}} = {{ – 89} \over {312}}\)