2,0 điểm) Thực hiện phép tính (tính hợp lí nếu có thể): a) 3 ⋅ 5 2 − 16 : 2 2 + 1. b) 43 + ( − 100 ) + ( − 43 ) + 150. c) 107 ⋅ 18 − 7 ⋅ 29 + 107 ⋅ 62 − 7 ⋅ 51. d) 2 0 − { 4 ⋅ [
Hướng dẫn giải
a) \[3 \cdot {5^2} - 16:{2^2} + 1\] \[ = 3 \cdot 25 - 16:4 + 1\] \[ = 75 - 4 + 1\] \[ = 71 + 1\] \[ = 72.\] c) \[107 \cdot 18 - 7 \cdot 29 + 107 \cdot 62 - 7 \cdot 51\] \( = \left( {107 \cdot 18 + 107 \cdot 62} \right) - \left( {7 \cdot 29 + 7 \cdot 51} \right)\) \( = 107 \cdot \left( {18 + 62} \right) - 7 \cdot \left( {29 + 51} \right)\) \( = 107 \cdot 80 - 7 \cdot 80\) \( = 80 \cdot \left( {107 - 7} \right)\) \( = 80 \cdot 100\) \( = 8\,\,000.\) | b) \(43 + \left( { - 100} \right) + \left( { - 43} \right) + 150\) \[ = \left[ {43 + \left( { - 43} \right)} \right] + \left[ {\left( { - 100} \right) + 150} \right]\] \( = 0 + 50\) \( = 50\). d) \({2^0} - \left\{ {4 \cdot \left[ {12 - {{\left( {3 - 6} \right)}^2} - \left( { - 2} \right)} \right]} \right\}:10\) \( = 1 - \left\{ {4 \cdot \left[ {12 - {{\left( { - 3} \right)}^2} + 2} \right]} \right\}:10\) \( = 1 - \left\{ {4 \cdot \left[ {14 - 9} \right]} \right\}:10\) \( = 1 - \left\{ {4 \cdot 5} \right\}:10\) \( = 1 - 20:10\) \( = 1 - 2\) \( = - 1.\) |