Câu 1:
d) $\frac{5.4^{15}-9^9-4. 3^{20}.8^9 }{5.2^9.6^{19}-7.2^{29}.27^6 }$
= $\frac{5.2^{30}. 3^{18}-2^2.3^{20}. 2^{27} }{5.2^9.2^{19}.3^{19}-7.2^{29}.3^{18} }$
= $\frac{2^{29}. 3^{18}(5.2-3) }{2^{18}.3^{18}(5.3-7.2) }=2$
e) $-2\frac{3}{7}:$ ($-12\frac{1}{2}$ $+15\frac{1}{7}).$ ($-3\frac{3}{10})-$ $(-\frac{34}{37})$.$(2\frac{1}{10}-$ $4\frac{2}{5})$
= $-\frac{17}{7}:$ ($-\frac{25}{2}$ $+\frac{106}{7}).$ ($\frac{-33}{10})-$ $(-\frac{34}{37})$.$(\frac{21}{10}-$ $\frac{22}{5})$
= $-\frac{17}{7}:$ ($\frac{37}{14}).$$(-\frac{33}{10})-$. $(-\frac{23}{10})$
= $\frac{34}{37}$
câu 2:
d) Ta có: $\frac{20}{11.13}$+ $\frac{20}{13.15}+..+$ $\frac{20}{53.55}=10($ $\frac{1}{11}$- $\frac{1}{13}$ +$\frac{1}{13}$ $-\frac{1}{15}$+..+ $\frac{1}{53}$ -$\frac{1}{53})$
= $=10(\frac{1}{11}-$ $\frac{1}{53})=$ $\frac{8}{11}$
Ta có pt: $\frac{0,2}{|2x-1|}-$ $\frac{20}{11.13}-...-$ $\frac{20}{3.55}=$ $\frac{3}{11}$
⇔ $\frac{0,2}{|2x-1|}-$ $\frac{8}{11}=$ $\frac{3}{11}$
⇔ $\frac{0,2}{|2x-1|}=1$ ⇔ $|2x-1|=0,2_{}$
⇔ \(\left[ \begin{array}{l}2x-1=0,2\\2x-1=-0,2\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=\frac{3}{5} \\x=\frac{2}{5} \end{array} \right.\)
