Rút gọn phân số:
\(a,\dfrac{31995-81}{42660-108}\)
\(b,\dfrac{3.5.7.11.13.37-10101}{1212120+40404}\)
\(\)
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A = \(\frac{3^4\left(5.79-1\right)}{2^2.3^2\left(5.79-1\right)}=\frac{9}{4}\); B = \(\frac{3.7.13.37\left(5.11-1\right)}{4.3.7.13.37\left(3.5-1\right)}=\frac{54}{4.14}=\frac{2.9}{4.2.7}=\frac{9}{28}\)
Câu a) \(\dfrac{31995-81}{42660-108}=\dfrac{31914}{42552}=\dfrac{31914:10638}{42552:10638}\)
=\(\dfrac{3}{4}\)
Câu b) \(\dfrac{\left(3.5.7.11.13.15.37-10101\right)}{121212+40404}\)
=\(\dfrac{\left(3.5.7.11.13.15.37-3.7.13.37\right)}{3.7.13.37.12+3.7.13.37.4}\)
=\(\dfrac{3.7.13.37\left(5.11.15-1\right)}{3.7.13.37\left(12+4\right)}\)
= \(\dfrac{824}{16}\)=\(\dfrac{103}{2}\)
A= [5.11.10101 -10101]/[10101.120+10101.4] = 10101.[5.11-1] / 101.[120+4] = 54/124=27/62
đúng nhé
\(a,A=\dfrac{201220122012}{201320132013}=\dfrac{201220122012:100010001}{201320132013:100010001}=\dfrac{2012}{2013}\)
\(b,B=\dfrac{3.5.7.11.13.37-10101}{1212120+40404}=\dfrac{5.11.10101-10101}{10101.120+10101.4}=\dfrac{10101.\left(5.11-1\right)}{10101.\left(120+4\right)}=\dfrac{54}{124}=\dfrac{27}{62}\)
Ta có:
\(A=\frac{3.5.7.11.13.37-10101}{1212120+40404}\)
\(=\frac{\left(3.7.11.13.37\right).5-10101.1}{120.10101+4.10101}\)
\(=\frac{10101.\left(5-1\right)}{10101.\left(120+4\right)}\)
\(=\frac{4}{124}=\frac{1}{31}\)
Sai rồi:
A = 5.11.(3.7.13.37) - 10101/(10101.120 + 10101.4)
= (5.11.10101 - 10101)/(10101.120+10101.4)
= 10101(5.11-1)/10101(120+4)
= 27/62.
.5.7.11.13.37-10101/1212120+40404
=3.5.7.11.13.37-10101/1212120.1/10+40404 (vì 1/1212120=1/121212.1/10)
= 3.37.7.11.13.5-101010/121212.1/100+40404
=111.1001.5-5/6.1/100+40404
=151515.5-250/3
=595959-250/3
=1787876/3
\(A=\frac{3.5.7.11.13.37-10101}{1212120+40404}\)
\(A=\frac{\left(3.7.13.17\right).\left(5.11\right)-10101}{120.10101+4.10101}\)
\(A=\frac{10101.55-10101.1}{120.10101+4.10101}\)
\(A=\frac{10101.\left(55-1\right)}{10101.\left(120+4\right)}\)
\(A=\frac{10101.54}{10101.124}\)
\(A=\frac{54}{124}\)
\(A=\frac{27}{62}\)
- chúc bn hok tốt
#Hạ
a: \(\dfrac{31995-81}{42660-108}=\dfrac{31914}{42552}=\dfrac{3}{4}\)
b: \(\dfrac{3\cdot5\cdot7\cdot11\cdot13\cdot37-10101}{1212120+40404}=\dfrac{545454}{1252524}=\dfrac{27}{62}\)
a, 31995−8142660−10831995−8142660−108
= 395.81−81395.108−108395.81−81395.108−108
=81.394394.10881.394394.108
= 8110881108 = 3434
b, 3.5.7.11.13.37−101011212120+404043.5.7.11.13.37−101011212120+40404
= 3.5.7.11.13.37−3.7.13.373.7.12.13.37.10+3.4.7.13.373.5.7.11.13.37−3.7.13.373.7.12.13.37.10+3.4.7.13.37
= (3.7.13.37)(5.11−1)(3.7.13.37)(120+4)(3.7.13.37)(5.11−1)(3.7.13.37)(120+4)
= 5.11−1120+45.11−1120+4
= 5412454124 = 2762