a) \(\frac{2}{3}+\frac{5}{3}x=\frac{5}{7}\)
\(\Rightarrow\frac{5}{3}x=\frac{5}{7}-\frac{2}{3}\)
\(\Rightarrow\frac{5}{3}x=\frac{1}{21}\)
\(\Rightarrow x=\frac{1}{21}:\frac{5}{3}\)
\(\Rightarrow x=\frac{1}{35}\)
Vậy \(x=\frac{1}{35}.\)
b) Ta có:
\(0,\left(27\right)+0,\left(72\right)=\frac{27}{99}+\frac{72}{99}=\frac{99}{99}=1.\)
\(\Rightarrow0,\left(27\right)+0,\left(72\right)=1\left(đpcm\right).\)
c) Ta có:
\(2^{300}=\left(2^3\right)^{100}=8^{100}.\)
\(3^{200}=\left(3^2\right)^{100}=9^{100}.\)
Vì \(8< 9\) nên \(8^{100}< 9^{100}.\)
\(\Rightarrow2^{300}< 3^{200}.\)
Chúc bạn học tốt!
