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a/\(\frac{2^3\cdot3^4}{2^2\cdot3^2\cdot5}=\frac{18}{5}\)\(\frac{2^4\cdot5^2\cdot11^2\cdot7}{2^3\cdot5^3\cdot7^2\cdot11}=\frac{2\cdot11}{5\cdot7}=\frac{22}{35}\)
b/\(\frac{121\cdot75\cdot130\cdot169}{39\cdot60\cdot11\cdot198}=\frac{11^2\cdot5^3\cdot13^3\cdot2\cdot3}{2^3\cdot3^4\cdot5\cdot11^2\cdot13}=\frac{5^2\cdot13^2}{2^2\cdot3^3}=\frac{4225}{108}\)
c/\(\frac{1998\cdot1990+3978}{1992\cdot1991-3984}=\frac{2^2\cdot3^3\cdot37\cdot5\cdot199+2\cdot3^2\cdot13\cdot17}{2^3\cdot3\cdot83\cdot11\cdot181-2^4\cdot3\cdot83}=\frac{2\cdot3^2\cdot11\cdot20101}{2^3\cdot3^3\cdot13\cdot17\cdot83}=\frac{11\cdot20101}{2^2\cdot3\cdot13\cdot17\cdot83}\)
Giải:
A=5/9+2/15-6/9
=(5/9-6/9)+2/15
= -1/9 + 2/15
= 1/45
B=2/7-3/8+4/7+1/7-5/8+5/15
= (2/7+4/7+1/7) + (-3/8-5/8) +1/3
= 1+ (-1) +1/3
=1/3
C=3/5+1/15+1/57+1/3-2/9-3/4-1/36
=9/15+1/15+1/57+19/57-8/36-27/36-1/36
=(9/15+1/15)+(1/57+19/57)+(-8/36-27/36-1/36)
=2/3+20/57+(-1)
=58/57+(-1)
=1/57
D=1/1.2+1/2.3+1/3.4+...+1/99.100
=1/1-1/2+1/2-1/3+1/3-1/4+...+1/99-1/100
=1/1-1/100
=99/100
Câu E mình ko biết làm nhé!
Bài làm
\(\frac{2}{3}.\frac{7}{15}-\frac{2}{3}.\frac{5}{27}\)
\(=\frac{2}{3}.\left(\frac{7}{15}-\frac{5}{27}\right)\)
\(=\frac{2}{3}.\left(\frac{63}{135}-\frac{25}{135}\right)\)
\(=\frac{2}{3}.\frac{38}{135}\)
\(=\frac{76}{405}\)
~ Nếu rút gọn đc rút hộ ~
\(-\frac{4}{9}.\frac{7}{15}+\frac{4}{9}.\frac{5}{27}\)
\(=-\frac{4}{9}.\frac{7}{15}-\left(-\frac{4}{9}\right).\frac{5}{27}\)
\(=-\frac{4}{9}.\left(\frac{7}{15}-\frac{5}{27}\right)\)
\(=-\frac{4}{9}.\left(\frac{63}{135}-\frac{25}{135}\right)\)
\(=-\frac{4}{9}.\frac{38}{135}\)
\(=\frac{152}{1215}\)
~ Rút gọn đc thì rút ~
# Chúc bạn học tốt #
\(\frac{\frac{2}{3}.\frac{7}{15}-\frac{2}{3}.\frac{5}{27}}{\frac{-4}{9}.\frac{7}{15}+\frac{4}{9}.\frac{5}{27}}=\frac{\frac{2}{3}.\left(\frac{7}{15}-\frac{5}{27}\right)}{\frac{4}{9}\left(\frac{-7}{15}+\frac{5}{27}\right)}=\frac{\frac{2}{3}}{\frac{4}{9}}=\frac{2:3}{4:9}=\frac{2.\frac{1}{3}}{4.\frac{1}{9}}=\frac{1.\frac{1}{3}}{2.\frac{1}{9}}=\frac{1}{6}\)
\(b=\text{}\dfrac{15.2^{24}.3^{14}-4.3^{15}.2^{24}}{19.2^{24}.3^{14}-6.2^{24}.3^{15}}=\)
\(=\dfrac{2^{24}.3^{14}\left(15-4.3\right)}{2^{24}.3^{14}\left(19-6.3\right)}=3\)