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a)\(\frac{10^3+2.5^3+5^3}{55}\)=\(\frac{5^3.2^3+2.5^3+5^3}{5.11}\)=\(\frac{5^3.\left(2^3+2+1\right)}{5.11}\)=\(5^2\)=\(25\)
b) \(2^x+2^{x+3}=144\)
\(\Rightarrow2^x+2^x.2^3=144\)
\(\Rightarrow2^x.\left(1+2^3\right)=144\)
\(\Rightarrow2^x=16=2^4\)
\(\Rightarrow x=4\)
c) \(2\left(x-5\right)+3\left(x-7\right)=10\)
\(\Rightarrow2x-10+3x-21=10\)
\(\Rightarrow5x-31=10\)
\(\Rightarrow5x=41\)
\(\Rightarrow x=\frac{41}{5}=8,2\)
Lần sau bạn nên viết đề rõ hơn nhé!
Đề: Tính nhanh: \(\frac{10^3+2\cdot5^3+5^3}{55}\)
ta có: \(\frac{10^3+2\cdot5^3+5^3}{55}=\frac{5^3\left(2^3+2+1\right)}{5\cdot11}=\frac{5^3\cdot11}{5\cdot11}=5^2=25\)
Học tốt nhé ^3^
\(\left|x\right|-3=4\)
\(\Rightarrow\left|x\right|=4+3\)
\(\Rightarrow\left|x\right|=7\)
\(\Rightarrow x\in\left\{-7;7\right\}\)
\(\frac{10^3+2.5^3+5^3}{55}=\frac{2^3.5^3+5^3\left(1+2\right)}{5.11}=\frac{8.5^3+5^3.3}{5.11}=\frac{5^3\left(8+3\right)}{5.11}\)
\(=\frac{5^3.11}{5.11}=\frac{5^3}{5}=5^2=25\)
Bài 1 :
\(\left|x\right|-3=4\)
\(\left|x\right|=7\)
\(\Rightarrow\orbr{\begin{cases}x=7\\x=-7\end{cases}}\)
Vậy...
Bài 2 :
\(\frac{10^3+2\cdot5^3+5^3}{55}\)
\(=\frac{2^3\cdot5^3+2\cdot5^3+5^3}{5\cdot11}\)
\(=\frac{5^3\cdot\left(2^3+2+1\right)}{5\cdot11}\)
\(=\frac{5^3\cdot11}{5\cdot11}\)
\(=5^2\)
\(\frac{-2}{3}-\left(\frac{-2}{5}\right)-\frac{7}{10}\)
\(=\frac{-10}{15}-\frac{-6}{15}-\frac{7}{10}\)
\(=\frac{-4}{15}-\frac{7}{10}\)
\(=\frac{-4}{15}+\frac{\left(-7\right)}{10}\)
\(=\frac{-40}{150}+\frac{-105}{150}\)
\(=\frac{-29}{30}\)
\(\left[\frac{11}{24}:\frac{55}{36}\right]\cdot\frac{10}{3}\)
\(=\left[\frac{11}{24}\cdot\frac{36}{55}\right]\cdot\frac{10}{3}\)
\(=\left[\frac{1}{2}\cdot\frac{3}{5}\right]\cdot\frac{10}{3}\)
\(=\frac{3}{10}\cdot\frac{10}{3}=1\)
\(\frac{10^3+2,5^3+5^3}{55}=\frac{1000+15,625+125}{55}=\frac{1140,625}{55}=20,738(63)\)
\(=\frac{5^3\left(2^3+2+1\right)}{5.11}=\frac{5^3.11}{5.11}=5^2=25\)