Thực hiện phép tính (tính hợp lý nếu có thể)
a) \(49.55 + 45.49\)
b) \(120:\left\{ {54 - \left[ {50:2 - \left( {{3^2} - 2.4} \right)} \right]} \right\}\)
Áp dụng các quy tắc tính cộng, trừ, nhân, chia, lũy thừa.
\(\begin{array}{*{20}{c}}{{\rm{a}})\,\,49.55 + 45.49 = 49.(55 + 45)}\\{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 49.100}\\{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 4900}\end{array}\)
\(\begin{array}{*{20}{c}}\begin{array}{l}{\rm{b)\;}}\,120:\left\{ {54 - \left[ {50:2 - \left( {{3^2} - 2.4} \right)} \right]} \right\}\\ = 120:\{ 54 - [50:2 - (9 - 8)]\} \end{array}\\\begin{array}{l} = 120:\{ 54 - [25 - 1]\} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\\ = 120:\{ 54 - 24\} \end{array}\\{ = 120:30 = 4\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}\end{array}\)
