Bài 5 trang 93 Tài liệu dạy – học toán 6 tập 1

Đề bài

Thực hiện các phép tính :

\(\eqalign{  & a)\;39.13 + 87.39  \cr   & b)\;15.42 – 18.32 + 3.42  \cr   & c)\;125.98 – 125.46 – 52.25  \cr   & d)\;80 – \left[ {130 – {{\left( {12 – 4} \right)}^2}} \right]  \cr   & e)\;135 – \left[ {1300 – {{\left( {{4^2} – 2.3} \right)}^3}} \right]:60  \cr   & g)\;50:\left\{ {2.\left[ {52 – {{\left( {3.5 – {2^3}.3} \right)}^3}} \right]} \right\}  \cr   & h)\;{7^{81}}:{7^{79}} + {5.5^2} – {2^3}.3  \cr   & i)\;{2.2^3} + {2^0}{.3^5} – 11. \cr} \)

Lời giải chi tiết

\(\eqalign{  & a)\;39.13 + 87.39 = 39(13 + 87) \cr&= 39.100 = 3900  \cr   & b)\;15.42 – 18.32 + 3.42 \cr&= 42.(15 + 3) – 18.32  \cr   &  = 42.18 – 18.32 = 18.(42 – 32)\cr& = 18.10 = 180  \cr   & c)\;125.98 – 125.46 – 52.25 \cr&= 125.(98 – 46) – 52.25  \cr   &  = 125.52 – 52.25 \cr&= 52.(125 – 25) = 52.100 = 5200  \cr   & d)\;80 – \left[ {130 – {{\left( {12 – 4} \right)}^2}} \right]\cr& = 80 – (130 – {8^2}) \cr&= 80 – (130 – 64) = 80 – 66 = 14  \cr   & e)\;135 – \left[ {1300 – {{({4^2} – 2.3)}^3}} \right]:60  \cr   &  = 135 – {\rm{[}}1300 – {(16 – 6)^3}{\rm{]}}:60 \cr&= 135 – (1300 – {10^3}):60  \cr   &  = 135 – (1300 – 1000):60 \cr&= 135 – 300:60 = 135 – 5 = 130  \cr   & g)\;50:\left\{ {2.\left[ {52 – {{\left( {3.5 – {2^3}.3} \right)}^3}} \right]} \right\}  \cr   &  = 50:{\rm{\{ }}2.{\rm{[}}52 – {(15 – 12)^3}{\rm{]\} }}\cr& = 50:{\rm{[}}2.(52 – {3^3}){\rm{]}}  \cr   &  = 50:{\rm{[}}2.(52 – 27){\rm{]}} \cr&= 50:(2.25) = 50:50 = 1  \cr   & h)\;{7^{81}}:{7^{79}} + {5.5^2} – {2^3}.3 \cr&= {7^{81 – 79}} + {5^{1 + 2}} – {2^3}.3  \cr   &  = {7^2} + {5^3} – 8.3 \cr&= 49 + 125 – 24 = 174 – 24 = 150  \cr   & i)\;{2.2^3} + {2^0}{.3^5} – 11\cr& = {2^{1 + 3}} + {1.3^5} – 11  \cr   &  = {2^4} + {3^5} – 11 \cr&= 16 + 243 – 11 = 259 – 11 = 248 \cr} \)

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