Rút gọn các phân số sau:
a.\(\frac{121212}{131313}\)
b.\(\frac{2^3.3^4}{2^2.3^2.5}\)
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Ta có:
\(\frac{2^2.2.3^2.3^2}{2^2.3^2.5}\) =\(\frac{2.3^2}{5}\) =\(\frac{18}{5}\)
Vậy
Ta cã: \(\frac{2^3.3^4}{2^2.3^2.5}\)
\(=\frac{2^2.2.3^2.3^2}{2^2.3^2.5}\)
\(=\frac{2.3^2}{5}\)
\(=\frac{18}{5}\)
\(\dfrac{2^3.3^4}{2^3.3^2.5}=\dfrac{1.3^2}{1.1.5}=\dfrac{9}{5}\)
\(\frac{2^3.3^4}{2^2.3^2.5}=\frac{2^2.3^2.2.3^2}{2^2.3^2.5}=\frac{2^2.3^2.18}{2^2.3^2.5}=\frac{18}{5}\)
\(\frac{2^3.3}{2^2.3^2.5}=\frac{2}{3.5}=\frac{2}{15}\)
Thiếu dấu nhân ở chỗ \(2^2.3^2\)nha
TA CÓ : \(\frac{2^3.3^4}{2^2.3^2.5}\)= \(\frac{2^3.3^4}{\left(2.3\right)^2.5}\)= \(\frac{2^3.3^4}{6^2.5}\)= \(\frac{2^3.3^4}{36.5}\)= \(\frac{8.81}{180}\)= \(\frac{648}{180}\)= 648 : 180 = 3,6 HOẶC \(\frac{648}{180}\)= \(\frac{18}{5}\)
\(a.\frac{2\cdot\left(-13\right)\cdot9\cdot10}{\left(-3\right)\cdot4\cdot\left(-5\right)\cdot26}\)
\(=\frac{2\cdot\left(-13\right)\cdot3\cdot3\cdot2\cdot5}{\left(-3\right)\cdot2\cdot2\cdot\left(-5\right)\cdot13\cdot2}\)
\(=-\frac{3}{2}\)
b) \(\frac{2^3\cdot3^4}{2^2\cdot3^2\cdot5}=\frac{2\cdot3^2}{5}=\frac{2\cdot9}{5}=\frac{18}{5}\)
\(\frac{2^4\cdot5^2\cdot11^2\cdot7}{2^3\cdot5^3\cdot7^2\cdot11}=\frac{2\cdot1\cdot11\cdot1}{1\cdot5\cdot7\cdot1}=\frac{22}{35}\)
c) \(\frac{121\cdot75\cdot130\cdot169}{39\cdot60\cdot11\cdot198}=\frac{11\cdot11\cdot13\cdot10\cdot169}{13\cdot3\cdot6\cdot10\cdot11\cdot11\cdot6\cdot3}\)
\(=\frac{169}{3\cdot6\cdot6\cdot3}=\frac{169}{324}\)
d) \(\frac{1998\cdot1990+3978}{1992\cdot1991-3984}\)
a)
\(y=\frac{2^3.3^4}{2^2.3^2.5}=\frac{2^2.2.3^2.3^2}{2^2.3^2.5}=\frac{2.3^2}{5}=\frac{18}{5}\)
b)\(y=\frac{1989.1990+3978}{1992.1991-3984}=\frac{1989.1990+1989.2}{1992.1991-1992.2}=\frac{1989.1992}{1992.1989}=1\)(vì tử bằng mẫu)
muốn rút gọn phân số đó ta làm như sau:
\(\frac{2^3\cdot3}{2^2\cdot3^2\cdot5}\)=\(\frac{2}{3\cdot5}\)=\(\frac{2}{15}\)
a)\(\frac{121212}{131313}=\frac{121212:10101}{131313:10101}=\frac{12}{13}\)
b)\(\frac{2^3\cdot3^4}{2^2\cdot3^2\cdot5}=\frac{2^2\cdot3^2\cdot3^2.2}{2^2\cdot3^2\cdot5}=\frac{3^2\cdot2}{5}=\frac{9\cdot2}{5}=\frac{18}{5}\)
a) 121212/131313 = 121212 : 1010/131313 : 1010 = 12/13.