Đề bài

Tính: a) \(\left( { - 10} \right) - 21 - 18\) b) \(24 - \left( { - 16} \right) + \left( { - 15} \right)\) c) \(49 - \left[ {15 + \left( { - 6} \right)} \right]\) d) \(\left( { - 44} \right) - \left[ {\left( { - 14} \right) - 30} \right]\)

Lời giải chi tiết

a) \(\left( { - 10} \right) - 21 - 18\)\(\begin{array}{l} = \left( { - 10} \right) + \left( { - 21} \right) - 18\\ =  - \left( {10 + 21} \right) +(-18)\\ = \left( { - 31} \right) +(-18)\\ =  - \left( {31 + 18} \right)\\ =  - 49\end{array}\)b) \(24 - \left( { - 16} \right) + \left( { - 15} \right)\)\(\begin{array}{l} = 24 + 16 + \left( { - 15} \right)\\ = \left( {24 + 16} \right) + \left( { - 15} \right)\\ = 40 + \left( { - 15} \right)\\ = 40 - 15\\ = 25\end{array}\)c) \(49 - \left[ {15 + \left( { - 6} \right)} \right]\)\(\begin{array}{l} = 49 - \left[ {15 - 6} \right]\\ = 49 - 9\\ = 40\end{array}\)d) \(\left( { - 44} \right) - \left[ {\left( { - 14} \right) - 30} \right]\)\(\begin{array}{l} = \left( { - 44} \right) + 14 + 30\\ =  - \left( {44 - 14} \right) + 30\\ =  - 30 + 30\\ = 0\end{array}\)

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