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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