rút gọn các phân số sau
a/ 2^3x3^4 / 2^2x3^2x5
2^4x5^2x11^2x7 / 2^3x5^3x7^2x11
b/ 121x75x130x169 / 39x60x11x198
c/1998x1990+3978 / 1992x1991-3984
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a,\(\frac{2^3.3^4}{2^2.3^2.5}=\frac{2.3^2}{5}=\frac{2.9}{5}=\frac{18}{5}\)
b, \(\frac{2^4.5^2.11^2.7}{2^3.5^3.7^2.11}=\frac{2.11}{5.7}=\frac{22}{35}\)
c,\(\frac{1998.1990+3978}{1992.1991-3984}=\frac{18.111.1990+18.221}{24.83.1991-166.24}\)
\(=\frac{18.\left(111.1990+221\right)}{24.\left(83.1991-166\right)}\)
\(=\frac{3.221111}{4.165087}=\frac{221111}{4.55029}=\frac{221111}{220116}\)
\(\)
Câu 1: \(\frac{121.75.130.169}{39.60.11.198}\)=\(\frac{11x11x15x5x130x13x13}{13x13x15x4x11x11x18}\)= \(\frac{5x130}{4x18}\)= \(\frac{650}{72}\)= \(\frac{325}{36}\)
Câu 2: \(\frac{1998.1990+3978}{1992.1991-3984}\)= \(\frac{3976020}{3962088}\)= \(\frac{994005}{990522}\)
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/\(\frac{1998\cdot1990+3978}{1992\cdot1991-3984}=\frac{2^2\cdot3^3\cdot37\cdot5\cdot199+2\cdot3^2\cdot13\cdot17}{2^3\cdot3\cdot83\cdot11\cdot181-2^4\cdot3\cdot83}=\frac{2\cdot3^2\cdot11\cdot20101}{2^3\cdot3^3\cdot13\cdot17\cdot83}=\frac{11\cdot20101}{2^2\cdot3\cdot13\cdot17\cdot83}\)