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\(\frac{5^4.20^4}{25^5.4^5}=\frac{5^4.5^4.4^4}{5^{10}.4^5}=\frac{1}{5^2.4}=\frac{1}{100}\)
Chúc hok tốt
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(A=4+4^2+4^3+...+4^{200}\)
\(4A=4^2+4^3+...+4^{201}\)
\(4A-A=3A=4^{201}-4\)
\(A=\frac{4^{201}-4}{3}\)
b) \(B=1+5+5^2+...+5^{2017}\)
\(5B=5+5^2+5^3+...+5^{2018}\)
\(5B-B=4B=5^{2018}-1\)
\(B=\frac{5^{2018}-1}{4}\)
c) \(C=\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{500}}\)
\(3C=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{499}}\)
\(3C-C=2C=1-\frac{1}{3^{500}}=\frac{3^{500}-1}{3^{500}}\)
\(C=\frac{\left(\frac{3^{500}-1}{3^{500}}\right)}{2}\)
T_i_c_k cho mình nha,có j ko hiểu cứ hỏi mình nhé ^^
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{5^4.20^4}{25^5.4^5}=\dfrac{\left(5.20\right)^4}{\left(25.4\right)^5}=\dfrac{100^4}{100^5}=\dfrac{1}{100}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\frac{5^5\cdot\left(4.5\right)^3-5^4\cdot\left(4.5\right)^3+5^7\cdot4^5}{\left(5^3\right)^3\cdot4^5}=\frac{5^8.4^3-5^7.4^3+5^7.4^5}{5^9.4^5}=\frac{5^7.4^3.\left(5-1+4^2\right)}{5^7.4^3.\left(5^2.4^2\right)}\)
= \(\frac{4+4^2}{5^2.4^2}=\frac{4.5}{5^2.4^2}=\frac{1}{4.5}=\frac{1}{20}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
cmt gi may co bai tu di ma lam bat ng ta lam cho may chep ha
\(2x+\frac{-1}{2}=\frac{-2}{3}\)
<=>\(2x=\frac{-2}{3}-\frac{-1}{2}=\frac{-1}{6}\)
<=>\(x=\frac{-1}{6}:2=-\frac{1}{2}\)
Vây \(x=-\frac{1}{2}\)
\(0.75-\left(-2x\right)=\frac{4}{5}\)
<=>\(\frac{3}{5}+2x=\frac{4}{5}\)
<=>\(2x=\frac{4}{5}-\frac{3}{5}=\frac{1}{5}\)
<=>\(x=\frac{1}{5}:2=\frac{1}{10}\)
Vậy \(x=\frac{1}{10}\)
\(\left(2x+5\right)\left(1-x\right)=0\)
<=>\(2x+5=0\)hoặc \(1-x=0\)
<=>\(x=\frac{5}{2}\)hoặc \(x=1\)
Vậy \(x=\frac{5}{2}\)hoặc \(x=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{5^4.20^4}{25^5.4^5}=\dfrac{\left(5.20\right)^4}{\left(25.4\right)^5}=\dfrac{100^4}{100^5}=\dfrac{1}{10}\)
\(\dfrac{5^4.20^4}{25^5.4^5}=\dfrac{\left(5.20\right)^4}{\left(25.4\right)^5}=\dfrac{100^4}{100^5}=\dfrac{1}{100}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{-5}{10}\)x\(\frac{-4}{10}\)x\(\frac{-3}{10}\)x\(\frac{-2}{10}\)x\(\frac{-1}{10}\)x \(0\) x...x\(\frac{4}{10}\)x\(\frac{5}{10}\)
= 0.
Chúc học tốt nhak bạn ^_^
\(\frac{5^4.20^4}{25^5.4^5}=\frac{\left(5.20\right)^4}{\left(25.4\right)^5}=\frac{100^4}{100^5}=\frac{1}{100}\)
mình đầu tiên
1/100 nhes http://olm.vn/hoi-dap/question/116928.html