Câu 139 trang 34 Sách Bài Tập (SBT) Toán lớp 7 tập 1: Tính G....

Tính

(G = {{45:left[ {47,375 – left( {26{1 over 3} – 18.0,75} ight).2,4:0,88} ight]} over {17,81:1,37 – 23{2 over 3}:1{5 over 6}}})

Giải

(G = {{45:left[ {47,375 – left( {26{1 over 3} – 18.0,75} ight).2,4:0,88} ight]} over {17,81:1,37 – 23{2 over 3}:1{5 over 6}}}) 

( = {{45:left[ {47,375 – left( {{{79} over 3} – 18.{3 over 4}} ight).2{2 over 5}:{{22} over {25}}} ight]} over {13 – {{71} over 3}:{{11} over 6}}}) 

(eqalign{
& = {{45:left[ {47{3 over 8} – left( {{{158} over 6} – {{81} over 6}} ight).{{12} over 5}:{{22} over {25}}} ight]} over {13 – {{142} over {11}}}} cr
& = {{45:left[ {47{3 over 8} – {{77} over 6}.{{12} over 5}:{{22} over {25}}} ight]} over {{{143} over {11}} – {{142} over {11}}}} cr} )

(eqalign{
& = {{45:left[ {47{3 over 8} – {{154} over 5}.{{25} over {22}}} ight]} over {{1 over {11}}}} cr
& = {{45:left[ {47{3 over 8} – 35} ight]} over {{1 over {11}}}} cr} )

(eqalign{
& = left( {45:12{3 over 8}} ight):{1 over {11}} = 45.{8 over {99}}.{{11} over 1} cr
& = {{45.8.11} over {99}} = 40 cr} )