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a. \(\frac{\left(-5\right)^2.20^4}{8^2.\left(-125\right)}=\frac{\left(-5\right)^2.5^4.2^8}{2^6.\left(-5\right)^3}=\left(-5\right)^3.2^2=\left(-125\right).4=-500\)
b, \(\frac{15^{11}.5^7.9^2}{5^{18}.27^6}=\frac{3^{11}.5^{11}.5^7.3^4}{5^{18}.3^{18}}=\frac{3^{15}.5^{18}}{5^{18}.3^{18}}=\frac{1}{3^3}=\frac{1}{27}\)
a) \(-\frac{8}{18}-\frac{15}{27}\)
\(=-\frac{4}{9}-\frac{5}{9}\)
\(=-\frac{9}{9}=-1\)
b) \(\frac{1}{2}\cdot\sqrt{100-\sqrt{\frac{1}{16}+\left(\frac{1}{3}\right)^0}}\)
\(=\frac{1}{2}\cdot\sqrt{100-\sqrt{\frac{1}{16}+1}}\)
\(=\frac{1}{2}\sqrt{100-\sqrt{\frac{17}{16}}}\)
Cái này ra số thập phân dài lắm
c) \(\frac{5^4\cdot20^4}{25^5\cdot4^5}=\frac{5^4\cdot5^4\cdot4^4}{5^5\cdot5^5\cdot4^5}=\frac{1}{100}\)
a) \(\frac{-8}{18}-\frac{15}{27}\)
\(=\frac{-4}{9}-\frac{5}{9}\)
\(=\frac{-9}{9}\)
\(=-1\)
b) \(\frac{1}{2}\sqrt{100-\sqrt{\frac{1}{16}+\left(\frac{1}{3}\right)^0}}\)
\(=\frac{1}{2}\sqrt{100-\sqrt{\frac{1}{16}+1}}\)
\(=\frac{1}{2}\sqrt{100-\sqrt{\frac{17}{16}}}\)
\(=\sqrt{\frac{1}{4}.100-\frac{1}{4}\sqrt{\frac{17}{16}}}\)
\(=\sqrt{25-\frac{\sqrt{17}}{16}}\)
c) \(\frac{5^4.20^4}{25^5.4^5}\)
\(=\frac{5^4.2^8.5^4}{5^{10}.2^{10}}\)
\(=\frac{5^8.2^8}{2^{10}.5^{10}}\)
\(=\frac{10^8}{10^{10}}\)
\(=\frac{1}{10^2}\)
\(=\frac{1}{100}\)
\(\frac{-8}{18}-\frac{15}{27}=\frac{-8.27-15.18}{18.27}=\frac{-216-270}{486}=-1\)
\(\frac{-5}{12}+0,75=\frac{-5}{12}+\frac{3}{4}=\frac{-5}{12}+\frac{9}{12}=\frac{1}{3}\)
\(3,5-\frac{-2}{7}=\frac{7}{2}-\frac{-2}{7}=\frac{7.7--2.2}{2.7}=\frac{49--4}{14}=\frac{53}{14}\)
a.
\(x\div\frac{11}{4}=-2,5\div\frac{5}{8}\)
\(x\div\frac{11}{4}=-2,5\times\frac{8}{5}\)
\(x\div\frac{11}{4}=-4\)
\(x=-4\times\frac{11}{4}\)
\(x=-11\)
b.
\(\frac{18}{5x+21}=\frac{27}{34}\)
\(5x+21=\frac{18\times34}{27}\)
\(5x+21=\frac{68}{3}\)
\(5x=\frac{68}{3}-21\)
\(5x=\frac{5}{3}\)
\(x=\frac{5}{3}\div5\)
\(x=\frac{5}{3}\times\frac{1}{5}\)
\(x=\frac{1}{3}\)
Chúc bạn học tốt ^^
